Fixed #2092: added a "is_secure()" method to HttpRequest which correctly handles the subtleties of mod_python's interaction with os.environ.  This one's been bugging me for about a *year*, so many many thanks to k.shaposhnikov@gmail.com for figuring it out, and Tim Shaffer for pointing out this ticket.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@3410 bcc190cf-cafb-0310-a4f2-bffc1f526a37