moves rating range/current challenge check into template in ChallengeGraph - fixes issue of
current challenge not appearing if it's outside the range because the template isn't updated
changes /game/spectate to /request/game in User
returns the game from User._addGame
checks for existing game in /game handler, and doesn't fire NewGame in User

(NewGame is for when a challenge has just been accepted - /game is now for
games that the client has request by id (which will usually be because they
are in the url))
adds handler for /challenge/accepted in User - fires NewGame to specifically indicate
that a challenge has just been accepted