Multiple "onUrl" and "offUrl" with "stateful" switches
Can you add multiple "onUrl" and "offUrl" with "stateful" switches?
When i use this
```
        {
			"accessory": "HTTP-SWITCH",
			"name": "Test",
			"switchType": "stateful",
			"onUrl": [
			"http://localhost/api/switch1On",
			"http://localhost/api/switch2On"
			],
			"offUrl": [
			"http://localhost/api/switch1Off",
			"http://localhost/api/switch2Off"
			],
			"statusUrl": "http://localhost/api/powerstate",
			"pullInterval": "10000",
			"statusPattern": "false",
			"auth": {
			"username": "user",
			"password": "pass"
			  }
        }
```
homebridge starts with this error
```
[2018-9-25 21:00:07] [TV Schlafzimmer] Error occurred while parsing 'onUrl': property cannot be an array!
[2018-9-25 21:00:07] [TV Schlafzimmer] Aborting...
```

When i use this
```
        {
			"accessory": "HTTP-SWITCH",
			"name": "Test",
			"switchType": "stateful",
			"onUrl": [
			{
			"url": "http://localhost/api/switch1On"
			},
			{
			"url": "http://localhost/api/switch2On"
			}
			],
			"offUrl": [
			{
			"url": "http://localhost/api/switch1Off"
			},
			{
			"url": "http://localhost/api/switch2Off"
			}
			],
			"statusUrl": "http://localhost/api/powerstate",
			"pullInterval": "10000",
			"statusPattern": "false",
			"auth": {
			"username": "user",
			"password": "pass"
			  }
        }
```
homebridge crashes on start.
Would be nice if you can add this festure.