Add Phusion Passenger

This pull request adds Phusion Passenger. It is an advanced process manager that's like a combination of Init, PM2, Cluster and Nginx combined in a single thing. This makes deployment a lot easier and significantly reduces the number of moving parts.

More info:

 * https://www.phusionpassenger.com/node_weekly
 * https://github.com/phusion/passenger/wiki/Phusion-Passenger:-Node.js-tutorial