adds gameSession to view and removes gameBoard from view
removes player1 and player2 from view, uses gameSession instead
add initializeGame(), getPieceID() and setMessage() functions to the main activity class
removes currentPlayer property from main activity, removes playerId parameter from  playTurn() in GameSession
fully moves game management from view to gameSession class; removes colTops[] from main activity class, fixes bug in playTurn() in GameSession
adds functions to handle gameplay, to be called in onClick listener
creates resource string for 'game is over'
allows user to select any tile to place chip
fixes move indicator bug
adds menu, allows user to start new game, quit