Update SyncMediaTypes to use ContentTypeService

Modeled after SyncDocTypes
Allows removal of tabs/properties not in XML files (based on DocType's
setting)
Merge remote-tracking branch 'origin/v2.2-Umbraco-7' into v2.2-Umbraco-7

Conflicts:
	Package/uSync/jumoo.usync.ui.dll
	Package/uSync/jumps.umbraco.usync.dll