auto merge methods refactored

Signed-off-by: Felix Gabel <felix.gabel@me.com>
CDKFetchController removed

Signed-off-by: Felix Gabel <felix.gabel@me.com>
CDKStack improved
NSManagedObjectContext+CoreDataKit

Signed-off-by: Felix Gabel <felix.gabel@me.com>
NSManagedObject+CoreDataKit added
init will only create a merged bundle from the main bundle
NSPersistentStore+CoreDataKit added
performBlockInBackground implemented
__autorelease removed
number of objects added to NSManagedObjectContext
minor bug fixed in +defaultDirectoryURL
NSFetchRequest (CoreDataKit) added
more improvements
CoreDataKit header clean up