Fix ng-services not able to start warden due to wrong rootfs

While deploying cf on OpenStack, a problem occurred while provisioning mongodb service. Problem was related to warden. It turned out warden wasn't able to create a container. The message received in the warden.log on the mongodb_node was: `/var/vcap/store/mongodb/containers/16toij4v21f/setup.sh: line 75: mnt/etc/hostname: No such file or directory`

The following fix has been verified to fix the mongodb problem locally, inspired by the way this is done in the dea_next job.