This patch adds a utility to the keystone API manager to retrieve the
identity endpoint's version data and retrieve the current version as a
tuple. As part of this work, this patch converts the deprecated usage of
keystoneclient alone to using keystoneclient in combination with a
keystoneauth session.
Change-Id: I37031b67ab2681e81022a75afcb4f41c5700c47b
656490fee2