Treat ping messages properly not to lose window title

Thanks to @rgawenda at #65.

resources/gotty.js

@@ -57,6 +57,7 @@
                 break;
                 break;
             case '1':
             case '1':
                 // pong
                 // pong
+                break;
             case '2':
             case '2':
                 term.setWindowTitle(data);
                 term.setWindowTitle(data);
                 break;
                 break;