Update TableOperation API, Fix core data delete

Moved the item property to the public api on table operations, removed
the constructors, and fixed core data store delete to use the passed in
query correctly
Local store upsert and delete use an array

Modify core data store and offline test helper to use updated
datasource protocol.
Flush out CoreDataStore implementation
Merge pull request #269 from phvannor/offline

iOS Clean up documentation, update local store