Simple playbook for Sahara and its dashboard

Right now there are no working puppet modules for Sahara and its
dashboard; the playbook follows the installation instructions
to configure the component.
It assumes that Sahara is installed on the controller node,
and the web server and mysql servers are running there too.

Change-Id: If85cafb6adfdf6572cca77afdbc7c62e10cb7a9e