Log identifiers of resources being cleaned up

On teardown compute API tests clean up resources such as servers
and images. This patch simply logs the identifiers of these
resources in order to help debugging failures which might originate
from problems during cleanup.

Change-Id: Ied2924bba78ec8f4a3b51df1be69273b28362475
Related-Bug: #1357055
Merge "Log identifiers of resources being cleaned up"