* 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.
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.