RFE: preflight check centos base pre-release packages

[wes hayutin]

Details:
https://trello.com/c/aYAxvefK/761-preflight-check-centos-base-updates

use the centos cr repo ( continuous release ) [1] repo to pre-flight check updates to centos.
RHEL 7.6 beta is out as of 8/22/2018, which means centos updates are not too far off.

Use featureset021 a non-voting ovb jobs in the promotion pipelines to use this repo to check updates. This means we may at times make fs021 voting at times or just check it by hand.

When the CentOS beta releases get close to releasing the TripleO community will need to follow and pay attention to featureset021 jobs.

[1]https://wiki.centos.org/AdditionalResources/Repositories/CR

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/595862

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/595862
Committed: https://git.openstack.org/cgit/openstack/tripleo-quickstart/commit/?id=d2bb7438254c1f61d9979196993b80ae78b6fc35
Submitter: Zuul
Branch: master

commit d2bb7438254c1f61d9979196993b80ae78b6fc35
Author: Wes Hayutin <email address hidden>
Date: Thu Aug 23 14:33:05 2018 -0400

    enable centos cr repo in featureset021, promotion jobs

    Ensure the latest CentOS base package updates and
    minor release updates do not break tripleo

    Closes-Bug: #1788675
    Change-Id: Ida0b644c9216eebe1d38ee72ead3da569d941f39

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/tripleo-quickstart 2.1.1 release.