Add KakuroCore as submodule/library

Add the KakuroCore repo as a submodule, and
add the KakuroCore project as a dependeny to
the KakuroGenerator product.
Make change xcode insists on

Commit a change xcode keeps making to
project.
Add gitignore
Add target to create PuzzleStore bundle

Add a target that builds and runs the KakuroGenerator
target, which generates puzzles based on arguments, and
then packages the resulting core data persistant store and
momd directory into a resource bundle.