Update Flask-OAuthlib to 0.7.0

The correct version was written in the setup.py (Flask-OAuthlib>=0.7.0) but the requirements.txt was at 0.6.0 which does not work with the current OAuth code and notably the authorized_response/handler as seen [here](https://flask-oauthlib.readthedocs.org/en/latest/api.html#flask_oauthlib.client.OAuthRemoteApp.authorized_handler).

Enjoy!