…entation.

Fixes #61
Fixes #490

`azurerm_virtual_machine_scale_set`: Support for updating the customData field

```
$ acctests azurerm TestAccAzureRMEventHubNamespace_maximumThroughputUnits
=== RUN   TestAccAzureRMEventHubNamespace_maximumThroughputUnits
--- PASS: TestAccAzureRMEventHubNamespace_maximumThroughputUnits (202.41s)
PASS
ok      github.com/terraform-providers/terraform-provider-azurerm/azurerm    202.432s
```

```
$ acctests azurerm TestAccAzureRMNetworkWatcher_
=== RUN   TestAccAzureRMNetworkWatcher_importBasic
--- PASS: TestAccAzureRMNetworkWatcher_importBasic (75.79s)
=== RUN   TestAccAzureRMNetworkWatcher_importComplete
--- PASS: TestAccAzureRMNetworkWatcher_importComplete (69.85s)
=== RUN   TestAccAzureRMNetworkWatcher_basic
--- PASS: TestAccAzureRMNetworkWatcher_basic (69.62s)
=== RUN   TestAccAzureRMNetworkWatcher_complete
--- PASS: TestAccAzureRMNetworkWatcher_complete (72.16s)
=== RUN   TestAccAzureRMNetworkWatcher_update
--- PASS: TestAccAzureRMNetworkWatcher_update (81.75s)
=== RUN   TestAccAzureRMNetworkWatcher_disappears
--- PASS: TestAccAzureRMNetworkWatcher_disappears (94.38s)
PASS
ok
```

…pdates

`azurerm_eventhub_namespace` - support for AutoInflating/MaximumThroughputCapacity

Intergrate with latest version of go-autorest to read access tokens through new way
customized through environment variable. The old behavior on local shell will be kept.

Notice: for Azure Cloud Shell user, please make sure that they're using latest patched
provider.

Note: As the Subscription specific Locks will break other tests; these tests need to be run individually.
As such I've introduced the `TF_ACC_SUBSCRIPTION_PARALLEL_LOCK`  environment variable for this purpose.

Tests pass:

```
$ TF_ACC_SUBSCRIPTION_PARALLEL_LOCK=1 acctests azurerm TestAccAzureRMManagementLock_
=== RUN   TestAccAzureRMManagementLock_importResourceGroupReadOnlyBasic
--- PASS: TestAccAzureRMManagementLock_importResourceGroupReadOnlyBasic (61.52s)
=== RUN   TestAccAzureRMManagementLock_importResourceGroupReadOnlyComplete
--- PASS: TestAccAzureRMManagementLock_importResourceGroupReadOnlyComplete (58.75s)
=== RUN   TestAccAzureRMManagementLock_importResourceGroupCanNotDeleteBasic
--- PASS: TestAccAzureRMManagementLock_importResourceGroupCanNotDeleteBasic (53.38s)
=== RUN   TestAccAzureRMManagementLock_importResourceGroupCanNotDeleteComplete
--- PASS: TestAccAzureRMManagementLock_importResourceGroupCanNotDeleteComplete (46.87s)
=== RUN   TestAccAzureRMManagementLock_importPublicIPCanNotDeleteBasic
--- PASS: TestAccAzureRMManagementLock_importPublicIPCanNotDeleteBasic (80.46s)
=== RUN   TestAccAzureRMManagementLock_importPublicIPReadOnlyBasic
--- PASS: TestAccAzureRMManagementLock_importPublicIPReadOnlyBasic (68.53s)
=== RUN   TestAccAzureRMManagementLock_resourceGroupReadOnlyBasic
--- PASS: TestAccAzureRMManagementLock_resourceGroupReadOnlyBasic (61.24s)
=== RUN   TestAccAzureRMManagementLock_resourceGroupReadOnlyComplete
--- PASS: TestAccAzureRMManagementLock_resourceGroupReadOnlyComplete (64.10s)
=== RUN   TestAccAzureRMManagementLock_resourceGroupCanNotDeleteBasic
--- PASS: TestAccAzureRMManagementLock_resourceGroupCanNotDeleteBasic (72.49s)
=== RUN   TestAccAzureRMManagementLock_resourceGroupCanNotDeleteComplete
--- PASS: TestAccAzureRMManagementLock_resourceGroupCanNotDeleteComplete (113.71s)
=== RUN   TestAccAzureRMManagementLock_publicIPReadOnlyBasic
--- PASS: TestAccAzureRMManagementLock_publicIPReadOnlyBasic (64.05s)
=== RUN   TestAccAzureRMManagementLock_publicIPCanNotDeleteBasic
--- PASS: TestAccAzureRMManagementLock_publicIPCanNotDeleteBasic (94.53s)
=== RUN   TestAccAzureRMManagementLock_subscriptionReadOnlyBasic
--- PASS: TestAccAzureRMManagementLock_subscriptionReadOnlyBasic (17.98s)
=== RUN   TestAccAzureRMManagementLock_subscriptionCanNotDeleteBasic
--- PASS: TestAccAzureRMManagementLock_subscriptionCanNotDeleteBasic (15.20s)
PASS
ok      github.com/terraform-providers/terraform-provider-azurerm/azurerm    872.839s
```

Fixes #23

Hotfix: upgrade packages under go-autorest to be v9.4.1.

New Resource: `azurerm_network_watcher`

Tests:
```
$ acctests azurerm TestValidateManagementLockName
=== RUN   TestValidateManagementLockName
--- PASS: TestValidateManagementLockName (0.00s)
PASS
ok      github.com/terraform-providers/terraform-provider-azurerm/azurerm    0.020s
```

New Resource: `azurerm_management_lock`

add test for issue #36

Updated the way user agent string gets assigned.

Avoid out of index errors when flattening image data disks.

…vironment from the SubscriptionID

Splitting out the authentication logic into a helpers folder
Also adding unit tests for these - which pass:

```
$ go test . -v
=== RUN   TestAzureFindValidAccessTokenForTenant_InvalidDate
--- PASS: TestAzureFindValidAccessTokenForTenant_InvalidDate (0.00s)
=== RUN   TestAzureFindValidAccessTokenForTenant_Expired
2017/11/30 15:02:01 [DEBUG] Token "7cabcf30-8dca-43f9-91e6-fd56dfb8632f" has expired
--- PASS: TestAzureFindValidAccessTokenForTenant_Expired (0.00s)
=== RUN   TestAzureFindValidAccessTokenForTenant_ExpiringIn
--- PASS: TestAzureFindValidAccessTokenForTenant_ExpiringIn (0.00s)
=== RUN   TestAzureFindValidAccessTokenForTenant_InvalidManagementDomain
2017/11/30 15:02:01 [DEBUG] Resource "https://portal.azure.com/" isn't a management domain
--- PASS: TestAzureFindValidAccessTokenForTenant_InvalidManagementDomain (0.00s)
=== RUN   TestAzureFindValidAccessTokenForTenant_DifferentTenant
2017/11/30 15:02:01 [DEBUG] Resource "https://management.core.windows.net/" isn't for the correct Tenant
--- PASS: TestAzureFindValidAccessTokenForTenant_DifferentTenant (0.00s)
=== RUN   TestAzureFindValidAccessTokenForTenant_ValidFromCloudShell
--- PASS: TestAzureFindValidAccessTokenForTenant_ValidFromCloudShell (0.00s)
=== RUN   TestAzureFindValidAccessTokenForTenant_ValidFromAzureCLI
--- PASS: TestAzureFindValidAccessTokenForTenant_ValidFromAzureCLI (0.00s)
=== RUN   TestAzureFindValidAccessTokenForTenant_NoTokens
--- PASS: TestAzureFindValidAccessTokenForTenant_NoTokens (0.00s)
=== RUN   TestAzureCLIProfileFindDefaultSubscription
--- PASS: TestAzureCLIProfileFindDefaultSubscription (0.00s)
=== RUN   TestAzureCLIProfileFindSubscription
--- PASS: TestAzureCLIProfileFindSubscription (0.00s)
=== RUN   TestAzurePopulateSubscriptionFromCLIProfile_Missing
--- PASS: TestAzurePopulateSubscriptionFromCLIProfile_Missing (0.00s)
=== RUN   TestAzurePopulateSubscriptionFromCLIProfile_NoDefault
--- PASS: TestAzurePopulateSubscriptionFromCLIProfile_NoDefault (0.00s)
=== RUN   TestAzurePopulateSubscriptionFromCLIProfile_Default
--- PASS: TestAzurePopulateSubscriptionFromCLIProfile_Default (0.00s)
=== RUN   TestAzurePopulateTenantAndEnvironmentFromCLIProfile_Empty
--- PASS: TestAzurePopulateTenantAndEnvironmentFromCLIProfile_Empty (0.00s)
=== RUN   TestAzurePopulateTenantAndEnvironmentFromCLIProfile_MissingSubscription
--- PASS: TestAzurePopulateTenantAndEnvironmentFromCLIProfile_MissingSubscription (0.00s)
=== RUN   TestAzurePopulateTenantAndEnvironmentFromCLIProfile_PopulateEnvironment
--- PASS: TestAzurePopulateTenantAndEnvironmentFromCLIProfile_PopulateEnvironment (0.00s)
=== RUN   TestAzurePopulateTenantAndEnvironmentFromCLIProfile_NormaliseAndPopulateEnvironment
--- PASS: TestAzurePopulateTenantAndEnvironmentFromCLIProfile_NormaliseAndPopulateEnvironment (0.00s)
=== RUN   TestAzurePopulateTenantAndEnvironmentFromCLIProfile_PopulateTenantId
--- PASS: TestAzurePopulateTenantAndEnvironmentFromCLIProfile_PopulateTenantId (0.00s)
=== RUN   TestAzurePopulateTenantAndEnvironmentFromCLIProfile_Complete
--- PASS: TestAzurePopulateTenantAndEnvironmentFromCLIProfile_Complete (0.00s)
=== RUN   TestAzurePopulateFromAccessToken_Missing
--- PASS: TestAzurePopulateFromAccessToken_Missing (0.00s)
=== RUN   TestAzurePopulateFromAccessToken_Exists
--- PASS: TestAzurePopulateFromAccessToken_Exists (0.00s)
=== RUN   TestAzureEnvironmentNames
--- PASS: TestAzureEnvironmentNames (0.00s)
=== RUN   TestAzureValidateBearerAuth
--- PASS: TestAzureValidateBearerAuth (0.00s)
=== RUN   TestAzureValidateServicePrincipal
--- PASS: TestAzureValidateServicePrincipal (0.00s)
PASS
ok      github.com/terraform-providers/terraform-provider-azurerm/azurerm/helpers/authentication    0.012s
```

Remove the field marked as "Removed" according to #572.

Support for managed service identity

…ck-tests

`azurerm_management_lock`: fixing the name validation

Conditional loading of the Subscription ID / Tenant ID / Environment

Test passes:

```
$ acctests azurerm TestAccAzureRMVirtualMachineScaleSet_extensionUpdate
=== RUN   TestAccAzureRMVirtualMachineScaleSet_extensionUpdate
--- PASS: TestAccAzureRMVirtualMachineScaleSet_extensionUpdate (593.13s)
PASS
ok      github.com/terraform-providers/terraform-provider-azurerm/azurerm    593.153s
```

`azurerm_virtual_machine_scale_set`: ensuring changes to the `settings` object are detected

```
$ acctests azurerm TestAccAzureRMLocalNetworkGateway_
=== RUN   TestAccAzureRMLocalNetworkGateway_importBasic
--- PASS: TestAccAzureRMLocalNetworkGateway_importBasic (82.23s)
=== RUN   TestAccAzureRMLocalNetworkGateway_basic
--- PASS: TestAccAzureRMLocalNetworkGateway_basic (81.29s)
=== RUN   TestAccAzureRMLocalNetworkGateway_disappears
--- PASS: TestAccAzureRMLocalNetworkGateway_disappears (79.17s)
=== RUN   TestAccAzureRMLocalNetworkGateway_bgpSettings
--- PASS: TestAccAzureRMLocalNetworkGateway_bgpSettings (78.70s)
=== RUN   TestAccAzureRMLocalNetworkGateway_bgpSettingsDisable
--- PASS: TestAccAzureRMLocalNetworkGateway_bgpSettingsDisable (96.18s)
=== RUN   TestAccAzureRMLocalNetworkGateway_bgpSettingsEnable
--- PASS: TestAccAzureRMLocalNetworkGateway_bgpSettingsEnable (97.39s)
=== RUN   TestAccAzureRMLocalNetworkGateway_bgpSettingsComplete
--- PASS: TestAccAzureRMLocalNetworkGateway_bgpSettingsComplete (79.68s)
PASS
ok      github.com/terraform-providers/terraform-provider-azurerm/azurerm    594.680s
```

```
$ acctests azurerm TestAccAzureRMLocalNetworkGateway_importBGPSettingsComplete
=== RUN   TestAccAzureRMLocalNetworkGateway_importBGPSettingsComplete
--- PASS: TestAccAzureRMLocalNetworkGateway_importBGPSettingsComplete (80.96s)
PASS
ok      github.com/terraform-providers/terraform-provider-azurerm/azurerm    80.987s
```

New Data Source: `azurerm_virtual_network`

This removes support for Publishing, since the SCM URL's aren't consistent across Sovereign Clouds (China/Germany/Govt etc)
Switches to using the new `default_site_hostname` field introduced in #612 rather than assuming what it is

Upgrading to v11.2.2-beta of the Azure SDK for Go

…y-bgp-settings

`azurerm_local_network_gateway` - support for BGP Settings

`azurerm_app_service` - Exporting the Default Hostname field

Provision sample for ASP.NET on azure_rm_app_service

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