Changes to work with flask-social pull request https://github.com/mattupstate/flask-social/pull/17

Usage example for the refactoring done in [this request](https://github.com/mattupstate/flask-social/pull/17).

Note that this should not be pulled unless the above request to flask-social is, and when that is done, the requirements should be updated to point back at the original flask-social (or the appropriate developer version).

Cheers!