When the front-end polls the back-end for the game-state, the back-end includes
a "date_updated" String in the JSON. If the String is the same as in the
front-end, then no updates are needed, but if they are not the same, then the
front-end will update the board. Because the front-end polls the back-end's
board state approximately every second, this should make the front-end more
efficient.