#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 
If we're killing, I'd kill all the media library files. It felt like too much but maybe it's right? Perhaps on a separate PR for easier reference?