Fix security issues (Procfile added gunicorn as safe fix)

You shouldn't use runserver in production:
https://docs.djangoproject.com/en/1.4/ref/django-admin/#runserver-port-or-address-port

As documentation state I quote:
"DO NOT USE THIS SERVER IN A PRODUCTION SETTING. It has not gone through security audits or performance tests. (And that's how it's gonna stay. We're in the business of making Web frameworks, not Web servers, so improving this server to be able to handle a production environment is outside the scope of Django.)"