HW10: Adjust size for mobile device

Url:
http://2-1-dot-banqi-smg.appspot.com/

The game need to be played horizontally in mobile device (tested in
iPhone 5s.) For this version, it does not need emulator.

Known bugs:
1. First move and first drage a piece will cause a popup indicating "The
operation could not be completed". But the move is valid and following
move and dnd won't cause the same error.
2. No sound... Yet the animation works.