Changed the way we register a prize for winner.
Now we have a new prize_selected boolean field on a winner. This is
used to filter on when finding what winners have not selected a prize
yet. This also replaces the previous method of removing virtualWinners
after they selected a prize.
PrelotteryWine also get's a winner reference. This is used to filter on
when finding what prizes are left, and also makes it easier to
archive/register a lottery when the wine has a winner attached.
