collector: Use oslo.messaging batch listener

[OpenStack Infra]

https://review.openstack.org/234831
Dear bug triager. This bug was created since a commit was marked with DOCIMPACT.
Your project "openstack/ceilometer" is set up so that we directly report the documentation bugs against it. If this needs changing, the docimpact-group option needs to be added for the project. You can ask the OpenStack infra team (#openstack-infra on freenode) for help if you need to.

commit 6bd9a3e97b8e747e1216c42a2794a84ddbf0a621
Author: Mehdi Abaakouk <email address hidden>
Date: Wed Oct 14 17:14:36 2015 +0200

    collector: Use oslo.messaging batch listener

    This change uses the batch oslo.messaging listener
    for the collector but configures it have the same behavior
    as the legacy one.

    DocImpact
    Depends-On: I16184da24b8661aff7f4fba6196ecf33165f1a77
    Change-Id: I3a2e54acadf790c5bb287a2c20ba09a890749cd9

[venkatamahesh (venkatamaheshkotha)]

https://github.com/openstack/openstack-manuals/blob/master/doc/config-reference/source/tables/ceilometer-collector.rst