Convert extractor to go + lua

[mjpitz]

I wrote the extractor process in TypeScript because it allowed me to get strict typing where I wanted it and duct typing when I needed it. While it's been convenient, I'm finding some drawbacks to the way the current serverside of gRPC in Node is implemented. By converging onto go, we'll likely make the process a bit smaller and simplify some of our deployment configuration.

Curious what others' thoughts are on this.

[mjpitz]

Another option could be to use something like otto: https://github.com/robertkrimen/otto

This would let us replace the core of the extractor process with go and have some basic javascript evaluation capabilities.