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).
If we're going to ever default it to True, far better to do it now than at any future time. 

If it were just about new users of this in Django, I'd say Zach is right and we should default it to True. My concern is about django-secure users (who have already tested HSTS and have a working config) moving to 1.8 and getting taken by surprise. But it's quite possible this wouldn't harm anyone in practice.

I'm not sure that the "opt-in" parallel with other settings is a reason to default it to False. Unlike other settings this is a secondary modifier to another setting, and HSTS in general is already opt-in.