Add Sync support for Saved Favorites w/ DI.FM Accounts

[austinkettner]

DI.FM Accounts have the ability to favorite channels and have these favorites saved to the account. With our own built-in Favoriting functionality we should enable support for syncing favorited channels to a users DI.FM Account automatically/seamlessly. Furthermore, if they have saved favorites when logging in we can fetch these and automatically propagate the favorites for that user.

This would be a feature alongside our current Windows 8 synced profiles/data which we use for favorites, allowing the favorites to be the across all Win8 devices. So completely additional functionality to our current setup.