Fixed #17101 -- Integrated django-secure and added check --deploy option

For background info, please see the [django-developers thread](https://groups.google.com/d/topic/django-developers/t8ybImtdnpM/discussion).
Added: 
```
Note that if Django isn't involved in serving user-uploaded files, this
setting won't help you. For example, if your :setting:`MEDIA_URL` is served
directly by your frontend Web server (nginx, Apache, etc.) then you'd want to
set this header there.
```