Initial NodeJS entity

WiP for a NodeJS entity, inspired by this [blog post](http://blog.carbonfive.com/2014/06/02/node-js-in-production/).

### TODO

- [ ] Write a better example application and a Java and YAML blueprint for same
- [ ] Add unit and integration/live tests
- [ ] Add NodeJS native [clustering](http://nodejs.org/api/cluster.html)
- [ ] Add an HAProxy load balancer and support for Nginx
- [ ] Improve GitHub repository cloning support (tags, commit ids, branches etc.)
Agreed; we should have a more holistic approach if this is the behaviour we want. It's a tricky one - sensors that were accumulate (e.g. total requests received) could be left as-is, but "most recent requests per second" should be zero'ed.