Refactor node.rb template

Please provide feedback only.
This PR just include the new template.

* Refactor / clean up existing code
* Store configuration in /etc/puppet/foreman.yaml instead of requiring changes to the template itself
* Add command line help
* Replace `--push-facts-parallel` with `--push-facts --parallel`
* Use gem rb-inotify to watch file changes (simpler to use)