Break Card Logic out of Board Class

[pongstylin]

In my quest to make the board class less monolithic by breaking out some logic to a separate Game class, I have determined that the card should continue to be managed by the board object, but via instantiating a new Card class. The Card object has a method that can take a unit object argument. Alternatively, it has a method that displays an arbitrary notice using the Trophy avatar and "Champion" name. The Trophy unit is instantiated and cached by the Card class.