Collision detection refactor

Bigger snake, bigger food, better collision detection, lots of new slightly wordy logic.
Rao and Jamie paired on the beginning of the new collision methods and driver code to test. Whoooooooo!

Paired with Jamie and Rao to finish up the collision methods.  

(There is also a new file called cool-snake, example code from a very awesome javascript snake game online for inspiration. http://codeincomplete.com/projects/snakes/)