Add an outlet collection for the Set Game card buttons
Create initialization stuff for the SetGameViewController
Update the UI when setting the card button outlets
Create updateUI method stub
Add SetGame class to the model

This class represents the logic for the game of Set.
Add public interface elements for the SetGame class
Add the cards property that holds all the cards in the game
Add lazy instantiation for the cards array
Add initializer for the SetGame class
Implement cardAtIndex public method
Add a Set game property and use lazy instantiation
Fix bug in validShading where the return values was nil
Return a SetCard instead of a Card, from the public cardAtIndex method of SetGame class
Implement the updateUI method
Change the way we create our color, because of a bug with CIColor

We create the color using the UIColor own method.