* Update edx-auth-backends and fix imports

* Update dependencies and fix new pylint errors

* Switch to alternative django-waffle fork

Current django-waffle master does not support management commands in Django
1.10+. The maintainer seems to have disappeared and hasn't merged any PRs in a
year.

This fork fixes the issues, but hopefully it will get merged into master in the
future and we can go back to installing django-waffle from pip.

* Pull freshly installed docker image for tests

* Don't use option "on" with waffle flag command

* Upgrade to Django 1.11.2

Will it just work?

* Use class based LogoutView and set redirect url

The function-based views are deprecated in Django 1.11. Except for
logout_then_login, which is still okay apparently.

* Use dispatch instead of get on InsightsLogoutView

* Address PR comments

* Use 0.25.1 of data api (also upgraded to 1.11)