added some minimax code.

Minimax is not functional yet, but I know I am close. I am getting confused with exactly what depth is supposed to. Somehow I am not returning the correct action either.
Minimax fully functional

MinimaxAgent passes all autograder test cases
Update multiAgents.py
Alpha Beta pruning fully functional

Reflex agent evaluation is still 9/10, but minimax and alpha-beta are 100%
Merge pull request #1 from dillon-blanksma/patch-1

added some minimax code.