"headers" parameter not working
**Describe the bug**
I'm trying to integrate **homebridge-http-switch** into my Homebridge system but when I try to add a device with it, including an header, it fails. I was trying to add a device with Authorization header in the following way:


```
{
    "accessory": "HTTP-SWITCH",
    "name": "Apple TV",
    "switchType": "toggle",
    "onUrl": {
        "url": "http://localhost:40304/Apple%20TV",
        "method": "POST",
        "body": "{ \"commands\": [ { \"key\": \"menu\", \"longPress\": false } ] }"
    },
    "offUrl": {
        "url": "http://localhost:40304/Apple%20TV",
        "method": "POST",
        "body": "{ \"commands\": [ { \"key\": \"home\", \"longPress\": true }, { \"key\": \"select\", \"longPress\": false } ] }"
    },
    "headers": {
        "Authorization": "TOKEN_APPLE_TV"
    }
}
```


**Expected behavior**
When I try to use the device it is calling the URL but the status of the response is always 401 Unauthorized because it is not reading properly the header. I tried from Postman and through curl from console and it is working good.


**Version** (output of `npm list -g homebridge homebridge-http-switch`)
 - homebridge: **1.1.0**
 - homebridge-http-switch: **0.5.30**


**Additional context**
I'm already using the plugin into the config, without headers, and it is working good.
