Groups portal infra code refactor

This patch removes the drush make site building function from
groups-dev instance, and now directly fetch release tarballs from
http://tarballs.openstack.org/groups repository. With an advanced
multi-slot deployment architecture it prevents the typical Drupal
WSOD issues that randomly caused site malfunction when a request
arrived during installation. It also simplifies the
deployment steps using the standard drush aliases and
drush-dsd extension and supports local configuration variables
in local_settings.php file.

Change-Id: I73976a60e080d15b6f513db79fee46bcf468e302
Merge "Groups portal infra code refactor"