Manage elasticsearch logstash indices.

* modules/openstack_project/manifests/logstash.pp: Add two cron jobs.
One to delete indices that are a week old and a second to optimize the
previous days' index.

Change-Id: I14767b3a590c04fa60cdc5ec350e6f49c155050b
Reviewed-on: https://review.openstack.org/26642
Reviewed-by: James E. Blair <corvus@inaugust.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins