[Fixed]-Django-medusa can't render wagtail

See the latest Wagtail docs – http://docs.wagtail.io/en/latest/reference/contrib/staticsitegen.html?highlight=medusa

django-medusa is no longer maintained, and is incompatible with Django 1.8 and above; the information below is retained for historical reference only. An alternative module based on the django-bakery package is available as a third-party contribution: https://github.com/mhnbcu/wagtailbakery