Add call to retrieve image metadata for volumes in bulk

When using the GET volume details REST API call, the image metadata API
contribution is making an individual db call for each of the available
volumes. When the number of volumes is large the details call can take
several minutes.

This patch adds a call to the volume.API to retrieve image metadata in
bulk, very similar to the one used to retrieve individual volume image
metadata.

Change-Id: Ic3aa721016704c72b7564cc5ceff71676806a24a
Partial-Bug: #1197612
(cherry picked from commit bb2daca2864a5607635a3aa37f3874fdda22797b)
Merge "Add call to retrieve image metadata for volumes in bulk" into stable/havana