Deploy Ceph in containers using ceph-ansible via external workflow

Deploy Ceph in containers using ceph-ansible via external workflow

Add docker profiles to deploy Ceph in containers via ceph-ansible. This is
implemented by triggering a Mistral workflow during one of the overcloud
deployment steps, as provided by [1].

Some new service-specific parameters are available to determine the workflow to
execute and the ansible playbook to use. A new `CephAnsibleExtraConfig`
parameter can be used to provide arbitrary config variables consumed by `ceph-ansible`.

The pre-existing template params consumed up until the Pike release to
drive `puppet-ceph` continue to work and are translated, when possible, into
the equivalent `ceph-ansible` variable.

A new environment file is added to enable use of ceph-ansible;
the pre-existing puppet-ceph implementation remains unchanged and usable
for non-containerized deployments.

1. https://review.openstack.org/#/c/463324/

Change-Id: I81d44a1e198c83a4ef8b109b4eb6c611555dcdc5