VMware: Add volume ID in vCenter's volume config

VMware: Add volume ID in vCenter's volume config

HP data protector's backup of vCenter inventory is failing
for 'in-use' Cinder volumes because the vmdk is attached
to two VMs (Nova instance and the backing VM corresponding
to Cinder volume). The solution is to skip the backing VM
during data protector's backup.

This patch adds key 'cinder.volume.id' with value set to
volume UUID in volume's vCenter config file so that other
vCenter solutions can uniquely identify Cinder volumes.

Closes-Bug: #1484012
Change-Id: I08a5f1a39def14f164ab3ca08a480310ce0b79ca