Add new OAuth2 tests
Properly fail to wrong Authorization token type
Change the django-oauth2-provider repository url

to point to my fork, which includes some bug fixes
Only add the django-oauth2-provider apps if the module is installed

otherwise log a warning
Avoid installing django-oauth2-provider for Python 3

the oauth2 module is not python 3 ready
Update the documentation

with a warning for incompatibility with Python 3
and taking @tomchristie advice into account on how to reformulate some
sentences