Modified the logic for validating scores

[LuqiPan]

Currently the logic doesn't account for deuce games, for example I just lost a game 15-17.

I think as long as we have the winner's score > 11 and loser's score at least 2 points less than winner's, we're good.

[colinpollock]

Hey, thanks for the pull request!

I think this will break the Elo scoring logic. There are two K values used: one for games to 11 and one for games to 21. In resource.py:GameListResource:post I checked whether the game was to 11 by checking whether winner_score == 11.

Currently you can enter deuce games as 11-10 or 21-20. This isn't explained well in the IRC bot's HELP.

So I think there are two potential ways forward:

1. Make it clear how to enter deuce games currently.
2. Update your branch to get whether the game is to 21 or 11 some other way.