Initial Keystone users, roles, domains, projects

Functions to create initial users, roles, domains and projects in
Keystone. Not doing endpoint registration yet.

Adds gettextutils (translations) to openstack-common.conf. Adds mock
dependency for testing.

Partially implements: blueprint tripleo-keystone-cloud-config

Change-Id: I8ad106c4dbf793bada4e4a1141256ac72bb653db