Changes course_membership checking decorator to redirect to login page

with redirect to originally intended page after login (closes #1883)
Shib support for this login redirect decorate
use view that does SSL upgrade/downgrade
a better way to do SSL upgrade/downgrade
Make shib login case more robust

Handle shib failure case to remove redirect loop
Lessen confusing messaging
default redirect to referer
bugfix: message.message
Merge pull request #2221 from Stanford-Online/jbau-1883-login-redirect

Jbau 1883 login redirect