Remove a TODO item related to oslo.messaging
Remove a TODO item related to oslo.messaging

Previously, we left a TODO item related to the version bump (a big one)
from oslo.messaging because we are not so sure there is nothing left to
be done for Senlin to adapt to such a change.
This patch is a double confirmation that the version bump is mostly
about oslo.messaing internals. We do NOT need to do any changes
accordingly.

Change-Id: I47497609ca9d8ff980f8881d4fc572664941bf87

openstack/senlin,stackforge/senlin,openstack/senlin,stackforge/senlin,openstack/senlin