Assign service role for ironic user
Assign service role for ironic user

We expect service role is assigned to a user who use service
user token feature.

Currently ironic uses it to communicate with glance, so we
should assign the role to ironic user in keystone identity.

Change-Id: Ib6836a7593d165466be34c63a20463a3b7b817a8

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