Created an Exception for the case where the piece at the described location in the board is not equal to the Piece requested for moves.
Adding NotMeException tests.
Adding toString method to ChessPiece for easier debugging.
Adding passing PawnTest for testNotMe.
Added a constraint that you should be able to return the moves for any piece equivalent to you.
Initial implementation of Pawn's getLegalMoves.

Needs more tests for more boundary conditions.