Patches for Kerberos with Active Directory

[Parsons, Aron]

Active Directory uses non-standard Kerberos principal names (e.g., HOSTNAME$) instead of
the more common host/hostname@REALM.  SPN queries fail (e.g., "Server not found in
Kerberos database") when you don't use the HOSTNAME$ version, even when the
proper service principals are added to the system.

These two patches allow Koji to be configured to play nicely in an Active Directory
environment when using Kerberos.

/aron