Remove the create-tarball.sh script.

We don't need this anymore, it was there to handle the milestone code.

Change-Id: Ie9b75fbeebd568d6d6fd47510a5083f26f214281
Reviewed-on: https://review.openstack.org/20660
Reviewed-by: Chuck Short <chuck.short@canonical.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Approved: Monty Taylor <mordred@inaugust.com>
Tested-by: Jenkins