As described here:
https://github.com/openstack/keystone/blob/master/keystone/resource/core.py#L841
https://github.com/openstack/keystone/blob/master/keystone/conf/identity.py#L21

* default project domain name MUST be named 'Default'
* default project domain id MUST be named 'default'
* default project user name MUST be named 'Default'
* default project user id MUST be named 'default'

Change-Id: I610a0416647fdea31bb04889364da5395d8c8d74