Generate keystone credentials for nailgun and ostf

* added keystone usernames for nailgun and ostf
* added generated keystone password for nailgun and ostf users

Implements: blueprint access-control-master-node-improvments
Change-Id: Iffbf4e5552b0c3db052ca42fe55832a865bcc7d5
Merge "Generate keystone credentials for nailgun and ostf"