#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 
Note here: saveContext is an async call. Any odds of race conditions between the `saveContext` actual execution, and the `success` callback?