Merge pull request #2 from elizabethengelman/human-vs-human

Human vs human
the program now ONLY plays with a dumb computer - need to change it to allow the user to choose who their opponent it
user can choose if they want to play against a human or computer, and if playing against the computer, they can choose to go first or second
edited tests
added tests for setup class
removed unnecessary comments and white space
refactored starter methods on the game class
refactored getting opponent and getting first or second - these methods now do not keep state
refactored tests and implementation of setup
added ability to choose smart computer
started to add minimax function
fixed a bug that didn't allow the user to choose 1st or 2nd while playing the smart comp
getting closer to minimaxing
finds the next move, but is currently not updated the board properly
rebased master (after merging the human-vs-human into master)