Add prefix for all container images used in a magnum cluster

[Spyros Trigazis]

An operator might want to pull the containers used in a magnum cluster from a private registry (secure or insecure).

* docker.io or gcr.io maybe unavailable or slow or maybe there are security concerns
* the magnum operator might want to use newer kubernetes versions than the supported ones or custom ones

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/pike
Review: https://review.openstack.org/497234

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/497223
Committed: https://git.openstack.org/cgit/openstack/magnum/commit/?id=69bb03fcbe87489ab3179d73bc7fc26d4a7befeb
Submitter: Jenkins
Branch: master

commit 69bb03fcbe87489ab3179d73bc7fc26d4a7befeb
Author: Spyros Trigazis <email address hidden>
Date: Thu Aug 24 12:03:00 2017 +0000

    k8s_fedora: Add container_infra_prefix label

    Add a label to prefix all container image use by magnum:
    * kubernetes components
    * coredns
    * node-exporter
    * kubernetes-dashboard

    Using this label all containers will be pulled from the specified
    registry and group in the registry.

    TODO:
    * grafana
    * prometheus

    Closes-Bug: #1712810
    Change-Id: Iefe02f5ebc97787ee80431e0f16f73ae8444bdc0

[OpenStack Infra (hudson-openstack)]

Change abandoned by Spyros Trigazis (strigazi) (<email address hidden>) on branch: stable/pike
Review: https://review.openstack.org/497234
Reason: This is late for pike

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/magnum 6.0.0 release.