Fix issue #17

Fixing issue #17.

Maybe it is necessary to mention that the shibboleth variables in HttpRequest.META are populated via wsgi. I do not know if this configuration is obvious. https://docs.djangoproject.com/en/dev/howto/deployment/wsgi/modwsgi/

Using Shibboleth headers is considered bad practice and generally unsafe. https://wiki.shibboleth.net/confluence/display/SHIB2/NativeSPAttributeAccess