publish JSONSchema for our JSON/YAML output

[jaypipes]

In preparation for a v1.0 release, I'd like to publish a versioned JSONSchema document that consumers may validate against (and also allow us to evolve our API over time). Part of our public API is the JSON/YAML that we produce when people marshal the ghw structs into JSON or YAML, so I'm conscious of changes to that public API. Having a versioned JSONSchema will allow us to deprecate and evolve things over time in a more controlled fashion.

[jaypipes]

@ffromani thoughts on this one? :)

[ffromani]

I like a lot and we need to add roundtrip tests!