Detect and log volumes from deleted projects.

This relates to bug 32369, cleaning up before project-deletion.

It seems too dangerous to actually delete volumes from this script;
so the actual deletion probably needs to wait until we have
direct API calls for volume creation and deletion.  Meanwhile,
this patch at least gets us notified about stray volumes.

Change-Id: I68e95683d03cdf70a4c8f71d3c532297abffb638
Merge "Detect and log volumes from deleted projects." into production