Utilise ['openstack']['region'] from cookbook-openstack-common

- Set ['openstack']['identity']['region'] to equal ['openstack']['region']
- Add tests for endpoint creation, to confirm region is set.

Change-Id: I7c2842a15508d6f04802ea3cce7fbd3cf3e91137
Addresses: blueprint uniform-region
Merge "Utilise ['openstack']['region'] from cookbook-openstack-common"