This patch adds a tab for cinder user messages for volumes and
snapshots. Cinder user messages shows error details for cinder
resources like if we are unable to create a volume due to some
failure in cinder it will shows us the reason of failure.
Implements blueprint cinder-user-facing-messages
Change-Id: I6f1539ffebdf2dfd0a470009e9171e868c2a9ad3