#30 Allow anonymous play

[Knitter]

It would be nice to allow users to play a game without registration. These games would not be recorded nor could the users be part of any score table but would allow new users to just jump into the game.
An option could be presented to the user that would allow him to login/register at the end and maintain the game he played, though that would probably require some change to the current database scheme that is heavily dependent on existing users (Game <-> User relation).