Added REST implementation for post formats
Merge branch 'develop' into issue/2551-blog-metadata
Implemented batched metadata sync in REST

Metadata now only includes options and post formats, media is synced
separately
Removed media syncing code
Removed BlogServiceRemoteProxy
Merge branch 'issue/2551-category-service' into issue/2551-blog-metadata
Drop batched operations

The way we use callbacks for our service and remote methods makes it
hard to batch operations when an error occurs.

If we're batching two operations (say option and formats sync) and one
fails, what do you do?

- Call `failure` once?
- Call `failure` twice?
- Do you call `overalSuccess` at all?

Also, the REST `/batch` method is not well documented

To keep it simple, the remote blog services now support single requests
only. If we move to a notification based syncing instead of callback
blocks, batching could become an interesting option
Moved blog-related methods out of AccountService
Merge branch 'develop' into issue/2551-blog-metadata

Conflicts:
	WordPress/WordPress.xcodeproj/project.pbxproj
Better check for deleted blog on callback

Refs #2667
Pass only object IDs to metadata handlers
Merge pull request #2601 from wordpress-mobile/issue/2551-blog-metadata

#2551 REST Cleanup: Blog metadata