allow the dev to log in as any user, always in admin group
Allowing the developer to log in as any user is important to work on web UI
which shows the "Review" column differently, if you're logged in as a user who
Always placing the user into the admin group is a quality of life improvement.
The default config is created with FAS_ADMIN_GROUP='', which prevents any admin
access until you correctly populate it (with "qa-admin"). That serves little
purpose. Instead, assign the admin group to the FakeFAS user automatically,
whichever its value is (even an empty string).