Also don't test Django 1.10 with Gitlab or Tox anymore

Some big updates were available, fixing compatibility with Django 1.11

Wolktm can't be deprecated because Django doesn't do longpolling

Luuk Scholten authored Sep 20, 2016 and Sébastiaan Versteeg committed Oct 10, 2016

Todo: make old link redirect to the dutch ical feed

This migrates members based on a JSON export from concrete5;
it recreates committees and boards, but does not yet do memberships

Joost Rijneveld authored Aug 25, 2016 and Thom Wiggers committed Aug 25, 2016

This is necessary to ignore errors in the django rest framework.

* Models and admin page for events
* Add organisers to events
* event overview page for organisers

Output is cleaned with `bleach` in the frontend

https://www.djangoproject.com/weblog/2016/aug/01/django-110-released/

Includes tests and an authentication backend to check the permissions
granted to committees.