#2551 REST Cleanup: Blog metadata

- Implemented post format sync in REST
- Added batched sync of options and post formats in REST
- No more media syncing
- Removed temporary BlogServiceRemoteProxy

Note I branched from #2570 so make sure to review/merge that one first

Refs #2551 
We're doing it this way everywhere, but it's a valid point. I think there's no problem: the object will be valid when success it's called, just not saved yet. success is called from the proper context, so as long as callers are aware that passed objects might not be saved yet we should be ok.