Use staticfiles, not STATIC_URL
Use staticfiles, not STATIC_URL

See:

- http://staticfiles.productiondjango.com/blog/stop-using-static-url-in-templates/
- https://docs.djangoproject.com/en/1.10/ref/templates/builtins/#std:templatetag-static
jgroszko/django-websocket-redis,jrief/django-websocket-redis,jgroszko/django-websocket-redis,jrief/django-websocket-redis