Actions:
Replaced isBlack variables with the new enum type PlayerColor
An IGameKeeper now has two InGamePlayer's, which can be used
to get a move from.
Created new enum type for game status, named GameStatus.
Created Move class for containing a move, from and to.
Created wrapper class for containing a move and the player
who made it.

TODO:
Change all the tests in RulesTest and all used methods in Rules
to make them use Move type instead of sending coordinates.
Implement history properly.
Make GameKeeper check for draw.