Flask OAuthlib relies on old Werkzeug

It will fail to import several things from werkzeug:

```
ImportError: cannot import name 'url_quote' from 'werkzeug'
```

Possible solutions are:

  * Pin older version of werkzeug
  * Refactor user functionality to use [lepture/authlib](https://github.com/lepture/authlib) as `flask-oauthlib` is no longer maintained.