allow json logs

[jtorjo]

need to get one first :)

[Peter-Optiway]

It would be great if you would add support for this, now that NLog has structured logging support. Example output:

{ "time": "2018-04-04 15:17:35.3798", "level": "INFO", "thread": "14 AsyncContext", "message": "Initializing web socket server" }
{ "time": "2018-04-04 15:17:35.4553", "level": "INFO", "thread": "14 AsyncContext", "message": "It took 139,4909 ms to initialize service", "elapsedMilliseconds": 139.4909 }
{ "time": "2018-04-04 15:17:35.5018", "level": "INFO", "thread": "14 AsyncContext", "message": "Starting background tasks" }