raffle winner announcement

[docrostov]

now that we've reached a pretty good adoption of the "/claim" command, it'd be cute if oaf did a post-rollover announcement of the day's raffle winners. the core issue is that (to my memory) we do not have any post rollover tasks. but it should be relatively straightforward to make a set of tasks that activate on daycount +1 (could just have oaf parse its daycount and check raffle winners if it's +1 what it was the time it last announced raffle winners).