After https://review.openstack.org/152321 was merged, it was no
longer guaranteed that some now deprecated settings like auth_host
and auth_protocol would be present in glance-api.conf. This breaks
the Glance provider, which expects them to be present.
This patch adds support for identity_uri in provider, while
keeping backwards compatibility.
Change-Id: Ie8a2e45a4afea4828e02af36e64d65e7d4b7557e
9f44421ceb