isValidCard, bug fixes, finishing touches..

-Fixed a bug where if there was a jack in a non null game, it sometimes
wouldn't win against non-jacks.
-Added end of game statistics to print out every players score.
-Added round error count to round statistics.
-Added total error count to game statistics.
-Made assignGamePoints call endGameInfo() on the player to let them know
if the declarer won. We should rename this to endRoundInfo() later.
-Removed isValidBid (unused since implementation of bidding changed from
ints to bools).
-Implemented isValidCard.
-Made DummyPlayer only play valid cards so it doesn't end our game with
a critical error of being unable to play multiple times.
-Added a few logging messages here and there, next update should
incorperate logging as much information as it can.