Drop require on keystone user and group
Drop require on keystone user and group

https://review.openstack.org/#/c/195684/ dropped the support
for managing the keystone user and groups. They are therefore no
longer in the catalog and we can't have a dependency on them.

Change-Id: Id16a77be2d850babb6e20a504dd78d35149b90eb

openstack/packstack,imcsk8/packstack,stackforge/packstack,stackforge/packstack,imcsk8/packstack,fr34k8/packstack,mahak/packstack,mahak/packstack,imcsk8/packstack,openstack/packstack,openstack/packstack,mahak/packstack,stackforge/packstack,fr34k8/packstack,fr34k8/packstack