Add docker_puppet_tasks initialization on primary node

Add docker_puppet_tasks initialization on primary node

This patch adds a new (optional) section to the docker post.j2.yaml
that collects any 'docker_puppet_tasks' data from enabled
services and applies it on the primary role node (the
first node in the primary (first) role).

The use case for this is although we are generally only using
puppet for configuration there are several exceptions that we
desire to make use of today for parity with baremetal. This
includes things like database creation and keystone endpoint
initialization which we rely on configuration via hiera variables
controlled by the puppet services.

Change-Id: Ic14ef48f26de761b0d0eabd0e1c0eae52d90e68a