Add missing service for DockerCinderVolumeImage
Add missing service for DockerCinderVolumeImage

OS::TripleO::Services::BlockStorageCinderVolume has a mandatory
DockerCinderVolumeImage parameter, but is missing an entry here, this
change adds that entry.

Change-Id: Ib818df1e2bcde3aa1713ad10b9aecc97d1b4eff8
Related-Bug: #1783653

openstack/tripleo-common,openstack/tripleo-common