[PATCH 1/2] pgarchives: Add missing authentication backend to settings.py

Hello,

Authentication when using private archives in pgarchives is broken with current settings.py file.
This first patch add a missing backend in settings.py, without which sessions aren't registered and users get
redirectedindefinitely.
 
In the second patch of this series, I add missing parameters for configuring PGAUTH, copying the ones from pglister.

Cheers,
-- 
Célestin Matte