Add PuzzleCore as a dependency

Add the iOS target of PuzzleCore as a
dependency
Display a static puzzle

Add an OPGamePlayViewController which will display
the entire game board, and an OPPuzzleGridViewController,
which will display only the puzzle grid. Add code to
OPPuzzleGridViewController to display a static puzzle.
Allow for basic scaling of puzzles

Place the OPPuzzleGridViewController's view inside
a UIScrollView to allow for zoom scaling.
Fade out level select when animating to puzzle
Add a basic keyboard

Add a keyboard to OPGameplayViewController.
Its only for looks, functionality will come in
a later commit.
Increase menu to puzzle transition speed
Fix keyboard spacing
Fix bug causing menu selection not to fade away

Fix bug causing menu selection to not fade away after
cancelling a menu to puzzle transition then panning
left.
Ensure puzzle grid is centered

Center the puzzle grid when it is scaled down