Before we could diferentiate the api version for identity because
the use of /v2 or /v3. Even though v2 is now deprecated, we need
to continue support previous versions of openstack. In this case
We cannot relay on the /v2 or /v3 in the url. The best user case
is to do a request in the base url (without any version) and
check if we have v3 version stable. If so, we assume identity
version is v3 otherwise, is v2.
Change-Id: Ia41d21ebad9329ae9fa506868957a72e6f9a5ca5