[test] Cover test for Game Room creating feature
[f] change the db design
	A game room now can have many users but only 1 host 
	User now belongs to one game room only
[f] Enable User to leave game
	User can leave game, when they do it, game is no longer related to user
	If host leave game, host position is transferred to other player
	If the last player leave , the game room is destroyed
[f] 060- Who is online?

Apply change when host or player leave game room to angularjs controller.
[https://www.pivotaltracker.com/story/show/83634060]