project overview and initial README.md

With links to the related resources and a summary of the goal of the
project as they were discussed on #puppet-openstack and

https://groups.google.com/a/puppetlabs.com/forum/#!topic/puppet-openstack/ibnrmXBAxVg

Change-Id: Ie4a45dcf06e944e6ca64f27cf3a129f6c9073cf1
Signed-off-by: Loic Dachary <loic@dachary.org>