Fix operation with 'noauth' backend
    
    With the noauth backend, user/groups are not set on the app context,
    so we can't check them in the requires_role wrapper; skip the checking
    if the backend is noauth.
    
    Automatically set login_disabled in the config, to avoid a confusing
    interaction between auth_backend and login_disabled.
    
    Remove the leftover AUTHORIZED_DISABLED in conf/config.py - it was
    no longer used for anything.