Fix Domain Model code example.
Fix Domain Model code example.

Tried running the code in the Domain Model examples in Glance docs
and realized it didn't work out of the box due to some minor errors.

Change-Id: Id4be33184e1729293b9cd9c91b8d0ab10ee41280

stevelle/glance,openstack/glance,stevelle/glance,rajalokan/glance,openstack/glance,openstack/glance,rajalokan/glance