Make OAuth packages optional

[rlucioni]

In most cases, only one OAuth package is necessary. This PR is a successor to #8, which made a similar change but didn't fix tests.

@jpadilla could you please review this? Let me know if you have any questions.

[jpadilla]

@rlucioni Thanks! We also need to update setup.py.

[rlucioni]

@jpadilla no problem. What in particular do we need to update in setup.py? python setup.py test succeeds after having installed the contents of requirements-test.txt.

[jpadilla]

@rlucioni https://github.com/jpadilla/django-rest-framework-oauth/blob/master/setup.py#L17

[rlucioni]

@jpadilla got it. Does it make sense to keep requirements.txt around given that it's now empty? I wasn't sure about deleting it.

[rlucioni]

@jpadilla I've updated setup.py.

[jpadilla]

@rlucioni Reviewing this more closely. Probably need some doc updates, right? What are the steps to get up and going after installing this package?

[rlucioni]

@jpadilla good call. I've updated the docs.

[rlucioni]

@jpadilla anything else I can do to help land this?

[jpadilla]

@rlucioni thanks! I'll cut out a release today.

[rlucioni]

@jpadilla that'd be great, thank you very much!

[jpadilla]

@rlucioni v1.1.0 is out, thanks again for everything! 🎆

[rlucioni]

@jpadilla awesome, thanks for the quick response.