Merge proxy-processor branch

[Haishi2016]

We need to work on merging the proxy-processor branch, unless this is overriden by the new remote agent work.
An associated issue is that when a stage is activated we are not including stage spec in the activation. In current implementation the process does another query back to the API to retrieve latest stage spec. We should probably change it so that the stage activation data is self-contained and no additional lookup is necessary.

[msftcoderdjw]

@Haishi2016 please rebase proxy-processor branch at first to unblock customer at first. We also have another task to support campaign on new remote agent.