Added code to support Core Data model with entities Palette and Color.

Major overhaul of the AppDelegate as well as setting up many of the DataSource delegate methods in the TVC.
So far everything builds ok and there are no runtime errors, but there is nothing in the database yet.
Saved Palette view functioning.

Updated lots of the code in the Core Data stuff behind the TableView.
Added a test case to pre-load two palettes with one color apiece to see
how the database retrievals were working and get a better feeling for the
table layout.
Added swipe-to-delete on the palette table.

You can now swipe across a row of the palette table to delete an entry.
If you delete the last entry in a palette, it is deleted also.