Set network proxy in config rather than jvm args

[lightningrob]

No description provided.

[codecov-io]

Codecov Report

Merging #1155 into master will decrease coverage by 0.05%.
The diff coverage is 52.5%.

@@             Coverage Diff              @@
##             master    #1155      +/-   ##
============================================
- Coverage      69.6%   69.55%   -0.06%     
+ Complexity     5248     5242       -6     
============================================
  Files           414      414              
  Lines         32323    32334      +11     
  Branches       4112     4113       +1     
============================================
- Hits          22500    22490      -10     
- Misses         8704     8717      +13     
- Partials       1119     1127       +8

Impacted Files	Coverage Δ	Complexity Δ
...in/java/com.github.ambry.cloud/CloudBlobStore.java	73% <100%> (ø)	18 <0> (ø)	⬇️
...main/java/com.github.ambry/config/CloudConfig.java	100% <100%> (ø)	1 <0> (ø)	⬇️
...com.github.ambry.cloud/azure/AzureCloudConfig.java	100% <100%> (ø)	1 <0> (ø)	⬇️
...mbry.cloud/azure/AzureCloudDestinationFactory.java	66.66% <20%> (-22.23%)	3 <1> (ø)
...ithub.ambry.cloud/azure/AzureCloudDestination.java	81.29% <51.61%> (+0.75%)	19 <2> (ø)	⬇️
.../main/java/com.github.ambry.store/ScanResults.java	81.25% <0%> (-3.13%)	16% <0%> (-2%)
...java/com.github.ambry.network/BlockingChannel.java	78.87% <0%> (-2.82%)	9% <0%> (-1%)
...b.ambry.network/BlockingChannelConnectionPool.java	70.43% <0%> (-1.74%)	9% <0%> (ø)
...in/java/com.github.ambry.store/BlobStoreStats.java	71.13% <0%> (-1.65%)	103% <0%> (-2%)
...va/com.github.ambry.replication/ReplicaThread.java	75.14% <0%> (-0.4%)	62% <0%> (-1%)

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[zzmao]

A few minor comments.

[jsjtzyy]

I don't have too much context of this PR. Only a few minor comments based on a cursory look. We can approve this after @zzmao 's comments are addressed.

[lightningrob]

Note: travis build failing due to Oracle JDK8 download. Sent email to travis support about it.
Ran gradle build/test locally and passed.

[zzmao]

LGTM.