Completed assignment 1

Key points:
- In CardMatchingGame,
   - created flipCardAtIndex interface fields - incremental score,
score, current card, cards to be matched to current cards. Philosophy
is that CardMatchingGame only maintains values, CardGameViewController
handles all text in the results label
   - simplified matching loop
   - made #Defines to be @Properties so can set values in getter
- In CardGameViewController for-loop handles updates to buttons. After
for-loop, all labels are set.
- Updated Score so matching 3  (or n) cards is higher score that
matching 2 cards