Add Contact/Collision Categories For All Game Elements

Add in the contact collision categories for all game elements in order to tell
which game elements can interact with each other. Also, move the instance
for white pad to be the default value in addChessBoard() in order to be
coincident with creating instance in addChessPeicesToBoard()
Fix Chess Pieces Name String To Not Use String Format

Because the chess pieces are using a string format along with the name of the
chess pieces in order to get the name of the image. This is causing issues with
checking the name of the chess piece as well as it does not look to good when
looking at the code.