Change krbContainer to allow ou attribute as kdb5_ldap_util in krb5
1.12.1 seems to have changed its behaviour and fails in realm
initialisation when put under ou=Kerberos Realms even if it already
exists. This may need to be changed later.
Use smbkrb5pwd_srv overlay instead of smbkrb5pwd
Fix file permissions properly for smbkrb5pwd_srv to work.