Grow.js node-red plugin

[JakeHartnell]

Ok, I think node-red is worth contributing to, it would be useful to make a Grow.js plugin for node-red. The use case is making a flow in the node-red ui that would allow for a growfile to be a rules engine for events.

We've made progress on integrating node-red into Grow-IoT (see #306). Luckily, it's relatively easy to embed in another application.