Sync Core Data via CloudKit

Ensembles 2 now supports Apple's new CloudKit framework as a backend for syncing Core Data stores. Anyone who has purchased an Ensembles package which includes source code access can find the new backend class in the GitHub repository. It will also be included in the next release.

CloudKit works at a lower level than iCloud document storage, behaving more like a traditional client-server setup. It should make working with iCloud much more predictable.