WIP: Integrating django-secure

For background info, please see the [django-developers thread](https://groups.google.com/d/topic/django-developers/t8ybImtdnpM/discussion).
Wasn't sure about this... it's rather verbose even dropping the `SECURE` prefix... `SECURITY_MIDDLEWARE_CONFIG['HSTS_INCLUDE_SUBDOMAINS']`. And in docs...