#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:**
**isDeleted** will return true only if the deletion wasn't already persisted. If the save OP was already executed, **isDeleted** may return false. Plus, checking if the **managedObjectContext** is nil, in order to determine if the object was nuked or not, is not safe (it's not a documented behavior).

The safest way to check if the blog is still valid, is by means of `existingObjectWithID:error:` selector.

[Reference here](http://stackoverflow.com/questions/4340445/how-can-i-tell-whether-an-nsmanagedobject-has-been-deleted/7896369#7896369)