Event presence (from admin pages) visible for normal users

Ghost User
2018-05-23T19:22:39+02:00

The value of the presence checkbox from the admin event pages should be visible on the event page of the regular website (and maybe the app)

### Desired behaviour
For the orientation barbecue we have to be able to take account of all people that are present at the barbecue. This in order to be able to fine people when they registered and did not show up. This was an issue last year. With the high number of people at the barbecue it is very likely that we will not be able to check presence for anyone.

Therefore, inspired by the pizza system from borrels, it would be nice if people can see whether we checked their presence. Then people can come to us and complain if we missed them immediately. Then we can simply say to members, if you are at the barbecue, make sure the light on the website turns green. Otherwise you will get the fine for not being present. (Of course this does not hold for the new first year students)

I think it is just making a field from the database visible on the website, so I think this should not be very complicated.