Added swagger-ui to document the API, create sandbox

Howdy, I just started using this project (nice job!) and thought it'd be helpful to have a sandbox for trying out the API.

The definition lives here:
https://github.com/fehguy/node-sonos-http-api/blob/master/docs/sonos.json

As I just got my sonos controller--and I just documented your api--I'm sure there are issues and improvements.  But this may be a good starting point.