Exclude custom FFA and 1v1 from casual elo

[GoogleFrog]

BattleResultHandler.SubmitSpringBattleResult needs modifying to not count these games for any ratings. Casual elo is important for keeping teamgames reasonable, but people should not feel like they can't screw around in custom 1v1s freely.

This is probably a reasonably easy thing for a new person to have a go at.

[Aquanim]

Ideally the FFA games would be placed in the rating category where old FFA games have been placed (I remember the number 16 is relevant), so that if we want a FFA ladder of some kind in the future it is easy to make.

Not sure what to do about casual 1v1s.