Warn Card Czar if not all players have submitted answers before 'pick a winner'

[FriendlyWP]

Right now, if the Card Czar clicks 'pick a winner', any players who haven't submitted answers yet are prevented from doing so. While this might be on purpose, sometimes it's a mistake and there's no way to re-invite a player to submit an answer after the CC has clicked 'pick a winner'.

A warning notice that 'not all players have submitted answers, are you sure you want to pick a winner?' would probably be enough to 'fix' it...? It just feels like a bug if you're not expecting it.

[KevinBongart]

Good idea and good candidate for an easy first contribution! Thanks @FriendlyWP