* Updated tox to test only python{2,3}.7 and djagno1.11/2.2
* Updated travis.
* Updated models/migrations.
* Updated path to `reverse`
* Updated path to login view.
* Updated middlewares/installed apps
* Updated .travis again.
* Lets see if that will get tests working in python3 on travis.
* Switch to in memory DB for tests
* Stop running tests with python2.7 and django 2.2. They shouldn't work anyway.
* Sure did that wrong. Fix which python versions are running with which code.
* That isn't needed. Lets see if that is what is breaking python3.
* Testing a theory.
* Revert "Testing a theory."
This reverts commit 69b3e4c906.
* Added initial migration for example users.
* is_authenticated is a bool, not a method.
* refs #1: Updated tox + travis.
* refs #1; Fixed path to register.
* refs #1: Updated urls.py
* refs #1: Added username field. Not really sure why it was needed, but whatever.
* Added an update note.
* refs #2: Updated travis.
* refs #2: Updated command to run tests.
* refs #2: Added a test showing permission_required is busted.
* refs #2: Custom user modal needs a default manager.
* refs #2: Updated settings.
* refs #2: Stop the exception from being raised.
* refs #2: Fixed a problem with named parameters.
1. All models need to be defined inside an installed application or declare an explicit app_label. Furthermore, it isn’t possible to import them before their application is loaded. In particular, it isn’t possible to import models inside the root package of an application
2. The django.contrib.contenttypes.generic module is removed
3. django.db.models.loading is removed.
As per [their blog post of the 27th April](https://blog.readthedocs.com/securing-subdomains/) ‘Securing subdomains’:
> Starting today, Read the Docs will start hosting projects from subdomains on the domain readthedocs.io, instead of on readthedocs.org. This change addresses some security concerns around site cookies while hosting user generated data on the same domain as our dashboard.
Test Plan: Manually visited all the links I’ve modified.
