Marconi fixes for precise

Fix a couple of problems found on Ubuntu:
* $MARCONI_DIR/etc/marconi/policy.json doesn't exist; removed the copy to /etc/marconi
* added a seting of nssize in /etc/mongodb.conf for Ubuntu
* restart the correct serice name on Ubuntu

Change-Id: I9bd2ab1aa4fb94ff96559e069e5b62138c358fb5
Revert the tempest service name to marconi

This patch is to rollback the change introduced by
https://review.openstack.org/#/c/73100/. 73100 is no longer needed
because of the recent https://review.openstack.org/#/c/69497/.
Using 'marconi' as the service name will keep us aligned with the
naming convention used by other projects.

Change-Id: I5da6d2aaeb5c9dc29a1cbc70c8425449807eb34c
Merge "Marconi fixes for precise"
Merge "Revert the tempest service name to marconi"