New game module and remote control

[colas-sebastien]

Here are the different modifications I did:

• dmd_game.py: new file containing the heart of the game. Thanks to inheritance we can know easily create new games without rebuilding everything from scratch
• dmd_game.py: contains now common command line arguments
• dmd_game.py: it is now possible to remote control the game thanks to web socket. The goal is to control the game via the PPUC project
• ws_client.py: a simple testing program to verify that remote control is working well
• dmd_snake.py: a new version that uses dmd_games.py