Fixed github link
keep track of channel name in Game
Replace (most) references to @game with game

This seems useless right now, but it allows us to change the initial
"game = @game" line of each method to be something more useful later on.
Add channel argument to !room

Required if in PM (because of multiple possible channels)
Optional if in channel (defaults to acting on that channel)
remove all references to @channel_name

In most cases these get replaced by a game.channel_name
In the case of devoice_channel we just pass in the channel