#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 
(Same as the other PR, sorry!): I know this wasn't changed, but you can just replace the last 4 lines with:

`return [results.allObjects firstObject]`