Failed authentication redirects to non-existent named 'login' view

[dleehr]

Consuming applications may define this view, but gcb-web-auth should only redirect to view names it provides

gcb-web-auth/gcb_web_auth/views.py

Line 82 in ad252da

return redirect('login')

[dleehr]

I found this when re-deploying dev this morning. The authenticate was returning None because I had removed myself from the group manager group.

But, rather than display an error message about not being in the correct group, it failed through to the redirect('login') call. Took quite a bit of time to figure out what was happening, so if we're going to keep the group manager stuff in place, we should report some errors.