Added REST support for blog syncing

Note that the syncBlogsForAccount: method is only called on the default
WordPress.com account, so we might as well drop XML-RPC support for it.

Refs #920 #1521

*Warning:* Jetpack sites are returned by me/sites but they won't work.
There's a bug in the API that returns the xmlrpc URLs as HTTPS, and we
don't even have the self-hosted credentials. We'll need to filter those
out until we fully support REST.
Filter out Jetpack sites from me/sites

They wouldn't work anyway since we don't have the credentials for the
site
No need to wait for merge blogs block

Since we're already passing the completion block to mergeBlogs: there's
no need to perform the block synchronously
Merge branch 'develop' into issue/1521-rest-account
Merge branch 'issue/add-media-progress-upload' into issue/1521-rest-media
Optimize images instead of multiple resizing options

Unless the user selected 'Original' for image processing, scale images down to
2048x2048. I chose 2048 since it'll allow for full width retina images
on most themes. Those with the odd giant image themes can always switch
to full size images.

Simplified media processing:

- Avoid unnecessary CGImage <-> UIImage conversions
- WPMediaMetadataExtractor can be replaced by a much simpler
  `representation.metadata`
- Removed WPMediaSizing
- Deprecated media.orientation
- Moved media creation to a new MediaService

Note that iOS seems to be ignoring CompressionQuality, although I don't
know why yet

See #1685
Don't compress full size images
Updated settings for optimized images
Merge pull request #1676 from wordpress-mobile/issue/1521-rest-account

Added REST support for blog syncing
Added size test for image optimizer
Merge branch 'develop' into issue/1685-optimize-images

Conflicts:
	WordPress/Classes/WordPressAppDelegate.m
	WordPress/WordPress.xcodeproj/project.pbxproj
Merge branch 'feature/rest' into issue/1521-rest-media
Merge branch 'issue/1685-optimize-images' into issue/1521-rest-media
Merge branch 'develop' of github.com:wordpress-mobile/WordPress-iOS into issue/1685-optimize-images

Conflicts:
	WordPress/Classes/ViewRelated/Media/WPMediaMetadataExtractor.h
	WordPress/Classes/ViewRelated/Media/WPMediaMetadataExtractor.m
	WordPress/Classes/ViewRelated/Media/WPMediaSizing.h
	WordPress/Classes/ViewRelated/Media/WPMediaSizing.m
	WordPress/WordPress.xcodeproj/project.pbxproj
Merge triage.
Restore test for the image optimizer.
Refactor media uploads into MediaServiceRemote
Replace WPMediaUploader with MediaService

Let EditPostViewController handle the upload queue
Added dotComID and restApi to Blog
Added REST media uploads