First pass

modularize scaffolding for node cluster

currently projects like cn, rtapi, ncar, pds all have a variant of this

please provide opinions

@Raynos @mrhooray @jsu1212 @kumikoda 
You should add the

```js
if (!(this instanceof Clustermon)) {
  return new Clustermon(options)
}
```

boilerplate to make the interface less hostile to forgetting to call `new` bugs.