Refactor KFData splitting "KFDataStore" out from Core

Closes #45
Remove addLocalStoreForced:

I don't think this was ever a good idea, but it won't work with write
ahead locks will will be used by default in future versions of OS X and
iOS.

Therefore I'm removing it.
Remove convinience methods for uncommon behaviour

There is no xDataStoreWithManagedObjectModel for memory stores. Once
there is iCloud store convinience methods it will result in there being
3-4 additional methods for this rather uncommon behaviour.

`[dataStore addLocalDataStore]` existed for this purpose.
Remove deprecated methods from previous release
Don't publically expose the persistent store coordinator

This shouldn't be used externally
Fix incorrect exception reason
Automatically re-fetch when persistent stores change
Expose objectAtIndexPath:
Remove outdated Kiwi based tests
Remove KFFetchedResultsTableController
Remove deprecated methods from the example application