This patch fixes issue with duplicate task IDs when multiple
loopback devices should be added, and they stored in the same
directory.

Change-Id: Iae0027b6ee187f5366967e667380dfb3eae232fc
Related-Prod: PROD-17620

This state allows to configure loopback device(s). This isn't meant to
be used in production but offers a cheap way to test Cinder with LVM
volumes.