Keystone is now deprecating the V2 API in favor of the V3 API.
The ceilometer client is now using the keystone session to
delegate the discovery of the version that is going to be used,
this eliminates the need of updating the client every time there
is a new API version.
DocImpact
blueprint support-keystone-v3-api
Change-Id: I6ebacce7adf70f24bdede9b920853ab9851071cf