remove kills from players, revert to sql counts

as apparently it's premature optimization (see migration code)
add limited game win functionality

with a short header in the overview indicating the game winner

FIXME: when there are just two players left, kill thinks it's itself or
something (i.e. it auto defaults to "your kill of x is pending")

        ^ will require some tricky business with model/controller

couple of things I haven't worked out- how often to check for winner

and the pauseish/stoppish behavior of games - which ones should be
allowed?