Better error stack and documentation

As of node v12 it will automatically display the entire stack (even if it's async). Added async to all promises for a much better stack.
The generator now has a way to document all the methods and parameters. Made a start with documenting the AVTransportService.

{
  "AVTransportService": {
    "Description": "Service that controls stuff related to transport (play/pause/next/special urls)",
    "File": "av-transport.service.ts",
    "Methods": {
      "BecomeCoordinatorOfStandaloneGroup": {
        "Description": "Leave the current group and revert to a single player."
      },
      "SnoozeAlarm": {
        "Description": "Snooze the current alarm for some time.",
        "Params": {
          "Duration": "Snooze time as hh:mm:ss, 10 minutes = 00:10:00"
        }
      },
      "Stop": {
        "Description": "Stop playback"
      }
    }
  }
}

svrooij / node-sonos-ts

Better error stack and documentation #33