kojira: Allow using Kerberos without krbV
    
    "Error: Unknown login error" message is very misleading because no
    authentication is being performed when krbV is not installed.
    
    Quit with error message if no authentication has been performed and also
    update such error message in kojid to mentioned cert auth.
    
    Signed-off-by: Igor Raits <ignatenkobrain@fedoraproject.org>