Upgrade of Cinder block storage nodes

Upgrade of Cinder block storage nodes

This introduces upgrades for Cinder block storage nodes. Currently
Cinder doesn't support upgrade level pinning and cannot safely deal with
version skew. This means that we have to upgrade Cinder storage nodes in
sync with controller nodes (after they were taken down for upgrade,
before they are brought back up) to ensure that Cinder services perform
AMQP communication only within the same major version of Cinder.

According to our current knowledge, Cinder block storage nodes are the
only node type that will have to be upgraded in sync with controllers.

Change-Id: Icec913c015eff744b0f31b513176b4b657df43af