Updated openstack/openstack
Project: openstack/taskflow  b78c8b8c0edc15b2b4d1bdb4293b191e258c851a

Use constants for revert automatically provided kwargs

Instead of using strings use module level constants for
the automatically provided keyword arguments to the tasks
revert function. This makes it easier for users of taskflow
to associate these constants with the actual keywords, without
having to resort to using raw strings directly.

Change-Id: I12726812615052d8405071d46272ef2b8286cfe2