created largestNumber method for grid class to return the largest number on a tile on the current grid
added resetPosition method to Tile class that sets the previousPosition to the current position
added canMoveInDirection method to game_manager in order to see if a user can move in a given direction
can now log runs to rails + keeps track of number of moves
added utility function for each direction
implemented a move based on the utility function written
renamed application.js to game.js to remove a conflict with rails