Run solar nodes as docker containers (Centos7 based)

[Bogdan Dobrelya]

This https://bugs.launchpad.net/solar/+bug/1547587 implements Ubuntu based solution.
We need another one, for Centos7 based.

After that, we should update the Atlas boxes and Vagrantfile for the virtualbox/libvirt providers for Centos7 as well.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/284782

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/286501

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/286501
Committed: https://git.openstack.org/cgit/openstack/solar/commit/?id=58683af802c2b6271245f9927a6bea74692c8ea9
Submitter: Jenkins
Branch: master

commit 58683af802c2b6271245f9927a6bea74692c8ea9
Author: Bogdan Dobrelya <email address hidden>
Date: Tue Mar 1 11:10:29 2016 +0100

    Fix riak container nested docker mounts

    Fix docker mounts to allow the riak docker container
    to be started nested.
    Also note about nested containers in the docs.

    Related-bug: #1548851
    Related-bug: #1547587

    Change-Id: I2fb448ac439b717eae1c3deee2cd067ac8b4f0c7
    Signed-off-by: Bogdan Dobrelya <email address hidden>

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/288525

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/284782
Committed: https://git.openstack.org/cgit/openstack/solar/commit/?id=467d84c6201230910c3bf69f6608a248e926c309
Submitter: Jenkins
Branch: master

commit 467d84c6201230910c3bf69f6608a248e926c309
Author: Bogdan Dobrelya <email address hidden>
Date: Tue Feb 23 16:02:09 2016 +0100

    Add centos7 docker support

    * Separate OSTYPE specific tasks/files.
    * Keep only common tasks and files in the
    playbooks dir.

    TODO pxe case to be working for centos as well
    note, the cmtools.sh installs ansible 2.0.1.0
      in centos7, while we have 2.0.0.2 for ubuntu trusty
    note, the base.yaml installs python-keystoneclient
      1:1.3.0-1.el7 from kilo-2 (no juno for centos7),
      while for ubuntu we have one from juno
    note, there is no pygraphviz for centos7, see also
      https://bugs.launchpad.net/fuel/+bug/1510884

    Closes-bug: #1548851

    Change-Id: Icec5637f9242104322d1104725f9f132d1ca16f0
    Signed-off-by: Bogdan Dobrelya <email address hidden>