Wafer

This release contains as broken migration due to rushing the release process. Do not use this release.

New features:
* A mechanism to add new users to specific auth groups: `WAFER_DEFAULT_GROUPS`.
* Two new default auth groups: "Page Content Editors", and "View All Talks"

Bug fixes:
* Long-standing schedule editor bug fixes. Dropped talks can now be removed again, without having to reload the page. (256).

Minor changes:
* Schedule editor unassigned talk list layout is now single-column.

Wafer 0.9.x supports Django 2 and 3 on Python 3.5+

Breaking Changes

* Dropped support for Python 2.x
* Dropped support for Django 1.11.x
* Dropped support for client-certificate based Debian SSO.

New Features

* Changed Select2 implementation from django-select2 to django-easy-select2
* Now compatible with drf-extensions 0.5 and djangorestframework 3.11.
* Added support for GitLab SSO.

Bug Fixes
* GitHub SSO should work again, after breaking with Django 1.10.
* Wafer now refuses to create a new account with an email address matching an existing account, when doing SSO.