Added GridView to the storyboard, added a proper gridView property to the LevelViewController, and set the storyboard's view to not Use Size Classes (to get a proper iPad preview).
Implemented all methods on the LevelViewController, which are startLevelNumber: and cellPressedAtRow:col:. I removed initializeGridView, initializeGridModel, and rotateClockwisePipeAtRow:col: from the LevelViewController, since I don't think they make sense. I needed methods to get the number of rows and columns from the GridModel, so I made a numRows and a numCols method for it.
I also created a PDCellPressedDelegate protocol, which I expect to be used for both the CellView and GridView. I updated the CellView and GridView's respective delegate properties to use this protocol. I also implemented the GridView's cellPressedAtRow:col: method, since it simply calls the same method on its delegate.
Merge pull request #6 from zsweedyk/storyboard-vc-setup

Vincent- Set up the storyboard and implemented the LevelViewController.