Wall Collision + Apple Spawn

Snake stays within bounds
Apple spawns initially in a random location within the screen
App has only one view which is portrait
Snake Collision with Apple

Detects when snake collides with the apple
Removes the apple and places a new apple on the screen
Snake Node Class

Snake node class
Keeps track of:
    -current pos
    - prev pos
    - current direction
Program has basic functionality and logic of snake
-Currently missing game over upon collisions