Handling timeouts gracefully
I have the following...

```
"accessories": [
        {
            "accessory": "HTTP-SWITCH",
            "name": "Fireplace",
            "switchType": "stateful",
            "timeout": 2000,
            "onUrl": "http://10.1.1.90/api/switchOn",
            "offUrl": "http://10.1.1.90/api/switchOff",
            "statusUrl": "http://10.1.1.90/api/switchStatus"
        }
    ],
```

If this device is unplugged or unreachable, everything in homebridge/home app goes red with "No Response". Is there something that can be done to handle the timeout gracefully? I first didn't have the timeout attribute and it was doing the same thing. I thought adding 2 seconds might help but the behavior is the same. 

Otherwise everything works great. Thanks for your support in creating this very useful plugin!
