Remove django-rest-auth as it's unmaintained

See Tivix/django-rest-auth#568

README.md

@@ -137,7 +137,6 @@ Twitter feed: [twitter.com/AwesomeDjango](https://twitter.com/AwesomeDjango)
 * [django-organizations](https://github.com/bennylope/django-organizations) - Multi-user accounts for Django projects.
 * [django-otp](https://bitbucket.org/psagers/django-otp/) - A pluggable framework for adding two-factor authentication to Django using one-time passwords.
 * [django-registration](https://github.com/macropin/django-registration/) -  Simple user-registration application for Django, designed to make allowing user sign-ups as painless as possible.
-* [django-rest-auth](https://github.com/Tivix/django-rest-auth) -  A set of REST API endpoints to handle User Registration and Authentication tasks.
 * [django-two-factor-auth](https://github.com/Bouke/django-two-factor-auth/) - User-friendly Two-Factor authentication.
 * [django-userena](https://github.com/bread-and-pepper/django-userena/) - Accounts for Django made beautifully simple.
 * [djoser](https://github.com/sunscrapers/djoser) - REST implementation of Django authentication system.