add md5 checksum for uc image
add md5 checksum for uc image

Today, when creating an uc backup, it generates a qcow2 file on Jenknis node
then it get copied to a remote storage(s).

The md5 checksum comes to verify that the copy was successful and worked as expected,
if the copy filed, the playbook will fail too and we won't use a corrupteed image
for snapshotting.

RHOSINFRA-3832

Change-Id: I7c8129f7cb3baa09a3ffab836d12cd023c57f176

redhat-openstack/infrared,redhat-openstack/infrared,redhat-openstack/infrared