Expose publish arguments to the API

[Flupster]

Example usage:

stream to: rtmp://localhost/live/channel?title=My%20Stream%20Title

Then they can go to http://localhost:8000/api/streams/live/channel

and will present them with

{
  "isLive": true,
  "viewers": 1,
  "duration": 0,
  "bitrate": 0,
  "startTime": "1970-01-01T00:00:00.000Z",
  "arguments": {
      "title": "My Stream Title"
  }
}