Add a page for raffling things

[macro1]

We should have a page that organizers can visit to raffle things off. The Meetup API can be leveraged to make the event from that time period available, and to list attendees and provide images to identify winners.

[hayleycd]

I want to try this.

[davidfischer]

We haven't had a giveaway in a while, but when we do I do the following:

• Get the attendees from meetup (as a CSV)
• Remove the organizers
• Randomly order them and take the top ~5-7 attendees. I take more than 1 because some people RSVP and then don't attend.

If this process could be automated, even with a management command (since it doesn't need to be public per se), that would save some time and make it repeatable. I haven't done much with the meetup API beyond what's already in the repository. However, if there's a way to take a meetup URL/event ID as input and output a randomized list of attendees, that seems useful.

Overall, I don't think this is high priority but it would be useful for when we have a giveaway.