Add OpenStack Chef Cookbook repositories

* Adds Chef cookbook repositories to Stackforge and related
  Zuul/Gerrit configuration

Cookbooks will be populated from a collection of "upstream"
repositories and eventually there will also be an example
meta-repo that contains reference role and environment
definition files and documentation on using the cookbooks
properly to set up an OpenStack deployment.

fixes lp 1176895

Change-Id: I02c17d2fb5522e63360453352489e237ba67347a
Reviewed-on: https://review.openstack.org/28306
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins