This change makes sure that the "self" property is ignored when
managing glance images, because the propery is read-only and not
supposed to be updated.
This issue was introduced by the switch to openstacksdk which was done
in openstackclient during Ussuri cycle so this doesn't affect Train
and older releases. In addition uring the following patch was merged in
openstacksdk during Victoria cycle and "openstack image show" no longer
includes the self propery in image properties since Victoria. So this
change is submitted only for Ussuri.