[bug 916079] Send HTTP users to /users/login which forces HTTPS. 

This is the agreed workaround for the Persona and HTTP issue.

To test it completely, you'd have to have a full http/https setup. If you do, awesome.

Otherwise, you can test the behavior on the devserver by setting `SESSION_COOKIE_SECURE=True` in `settings_local.py` and clicking on the "Sign in with email" link. It should take you to /users/{login,auth} depending on if mobile or desktop. Signing in won't actually work because it sets the cookies to secure and you are on http. So it goes a little nuts.

r?