Added persistence of game state to localstorage after each move

Added rebuilding of game state from localstoage on page load
Added New Game button to allow game restarts now that refreshes resume the game

js/tile.js

@@ -15,3 +15,13 @@ Tile.prototype.updatePosition = function (position) {
   this.x = position.x;
   this.y = position.y;
 };
+
+Tile.prototype.tileState = function () {
+    return {
+        position: {
+            x: this.x,
+            y: this.y
+        },
+        value: this.value
+    };
+}