To be able to support multiple hosts working with the same resources we
have added the workers table to keep track of which host is working with
each specific resource.
This patch makes c-vol service work with this new table by adding
entries on cleanable operations and removing them once these operations
have completed.
Service cleanup on initialization has also been changed to use this new
table so hosts will cleanup only resources from operations they left on
the air and leave any operations that are being processed by other
hosts.
Specs: https://review.openstack.org/236977
Implements: blueprint cinder-volume-active-active-support
Change-Id: I4e5440b8450558add372214fd1a0373ab4ad2434
d2ec578725