Improve Concurrency Support

[brianghig]

In order to increase the scalability of applications built on the node-rest-starter, we can improve support for concurrent applications. With the current codebase, we're limited to running multiple services at the OS / VM level in order to provide horizontal scalability. However, the Node.js community provides mechanisms for running multiple processes (workers) on a single instance that can effectively use more available CPUs.

One way to improve scalability is to provide out-of-the-box support for a configurable number of multiple application processes with a single instance of a node-rest-starter service.