FreeIPA: Make OTP and FreeIPA server parameters optional
FreeIPA: Make OTP and FreeIPA server parameters optional

In the freeipa-enroll.yaml, it can be the case that the node has been
enrolled (via a cloud-init script); in this case, the OTP and the
FreeIPA server are optional. However, we still need to get a kerberos
ticket, which is the last step of this script, since this ticket is what
certmonger will use to request the certificates in subsequent steps.

Change-Id: I7e9d6a747cdcbe81c9a74a17db5e91aa9d459f65

openstack/tripleo-heat-templates,dprince/tripleo-heat-templates,openstack/tripleo-heat-templates,dprince/tripleo-heat-templates