Since CIFS principal is generated by ipa-adtrust-install and is only
usable after setting CIFS configuration, there is no need to include it
into default setup.
This should fix upgrades from 2.2 to 3.0 where CIFS principal does not
exist by default.
https://fedorahosted.org/freeipa/ticket/3041
We need two attributes in the ipaNTTrustedDomain objectclass to store different
kind of SID. Currently ipaNTSecurityIdentifier is used to store the Domain-SID
of the trusted domain. A second attribute is needed to store the SID for the
trusted domain user. Since it cannot be derived safely from other values and
since it does not make sense to create a separate object for the user a new
attribute is needed.
https://fedorahosted.org/freeipa/ticket/2191
