WIP geard - Support additional systemd slices

* Add container-large systemd slice unit
WIP geard - Support additional systemd slices

* Update documentation
Merge pull request #169 from jwhonce/origin_node_472

origin_node_472 Support addtional systemd slices
Initial implementation of 'docker-notify' wrapper
Added support for 'notify' geard deployment
Added sample notify_deployment.json