Adapt the web UI to use the Agama network service

[imobachgs]

Problem

The web UI still talks directly to NetworkManager to set up network connections.

Solution

This is the first set of changes aimed to stop using the NetworkManager service from the web UI. Instead, it should talk to Agama's network service (which relies on NetworkManager itself).

This pull request adapts the web UI to use Agama's network service to write the changes (including connecting to wireless devices). However, the status information is still retrieved from NetworkManager because those bits are missing from our API.

During the process, we needed to introduce a few changes to Agama's network service:

• Use UUIDs to identify connections instead of the Id (the name).
• Write only changed network connections.
• Rollback to the previous state if some connection cannot be updated.
• Better error handling at D-Bus level.

Future

• Improve (almost non-existent) error handling.
• Retrieve the status information from Agama's network service.

Testing

• Adapted unit tests
• Tested manually

[coveralls]

coverage: 74.509% (-0.2%) from 74.667%
when pulling 878ca8f on use-agama-network
into 1968c26 on master.

[joseivanlopez]

Looks great! Only minor comments.

[joseivanlopez]

NP: What do think about renaming this method to AddOrUpdateConnection ?

[imobachgs]

I thought about that, but it is weird having an addOrUpdateConnection and updateConnection. Perhaps we might need to merge them and have something like saveConnection only. I will think about that.

[joseivanlopez]

LGTM