Handle more participants
Currently, we can't handle much participants. We are limited to ~300 without exclusions. We should be able to handle more. Some suggestions:
- Make the resolution of draw async via worker. Then send an email to the organizer if something's wrong + the csv to reimport what they filled. Probably should also include title and body of the mail? Probably better with #87 (closed) before to validate organizer email.
- Paginate the participants listing in the organizer page. Add some search/filtering.
- Test limit for download sync. Maybe send by mail? Check size limit too.