HS100 not automatically detected
### Expected Behavior
After installing the TPLink smarthome plugin and using the given config, the HS100 should show up in the Home app.

### Current Behavior
HomeBridge launches fine, but the HS100 is not detected.

### Steps to Reproduce (for bugs)
1. Install HomeBridge and the TPLink plugin.
2. Use the config.json file that is supplied with TPLink plugin.
3. Launch HomeBridge.

### Versions
<!-- Please run commands and include versions below. -->
- **Node**:      8.9.4
- **Homebridge**: 0.4.38
- **OS**:         Windows 8.1 (64 bit)

### Configuration
<!-- Please include the TplinkSmarthome platform section of your config.json file.
Paste between the two ``` lines below.
-->
```json

{
    "bridge": {
        "name": "Homebridge",
        "username": "CC:22:3D:E3:CE:30",
        "port": 51826,
        "pin": "031-45-154"
    },

    "description": "This is an example configuration file.",

    "platforms": [{
        "platform": "TplinkSmarthome",
        "name": "TplinkSmarthome"
    }],

    "accessories": []
}
```

### Homebridge Log / Command Output
<!-- Paste relevant output between the two ``` lines below
  - Remove any sensitive information, passwords, etc.
  - If output is long:
    - Please extract only the relevant portions if possible (remove other plugin's output, etc)
    - Consider creating a gist, etc
  - However, please include the beginning of the log where the homebridge initialization happens if possible
-->
```

[2018-4-9 18:34:19] Loaded plugin: homebridge-tplink-smarthome
[2018-4-9 18:34:19] Registering platform 'homebridge-tplink-smarthome.TplinkSmar
thome'
[2018-4-9 18:34:19] ---
[2018-4-9 18:34:19] Loaded config.json with 0 accessories and 1 platforms.
[2018-4-9 18:34:19] ---
[2018-4-9 18:34:19] Loading 1 platforms...
[2018-4-9 18:34:19] [TplinkSmarthome] Initializing TplinkSmarthome platform...
[2018-4-9 18:34:19] [TplinkSmarthome] homebridge-tplink-smarthome v3.11.0, node
v8.9.4, homebridge v0.4.38
[2018-4-9 18:34:19] [TplinkSmarthome] config.json: {"platform":"TplinkSmarthome"
,"name":"TplinkSmarthome"}
[2018-4-9 18:34:19] [TplinkSmarthome] config: {"platform":"TplinkSmarthome","nam
e":"TplinkSmarthome","addCustomCharacteristics":true,"deviceTypes":[],"switchMod
els":["HS200"],"discoveryOptions":{"discoveryInterval":10000,"deviceTypes":[],"d
eviceOptions":{"timeout":5000},"macAddresses":[]}}
[2018-4-9 18:34:19] Loading 0 accessories...

[2018-4-9 18:34:20] [TplinkSmarthome] didFinishLaunching
[2018-4-9 18:34:20] [TplinkSmarthome.API] client.startDiscovery({"discoveryInter
val":10000,"deviceTypes":[],"deviceOptions":{"timeout":5000},"macAddresses":[]})

[2018-4-9 18:34:20] Homebridge is running on port 51826.
[2018-4-9 18:34:20] [TplinkSmarthome.API] client.socket: UDP IPv4 listening on 0
.0.0.0:55412
[2018-4-9 18:34:20] [TplinkSmarthome.API] client.sendDiscovery(255.255.255.255,
undefined, 3)
[2018-4-9 18:34:30] [TplinkSmarthome.API] client.sendDiscovery(255.255.255.255,
undefined, 3)

```
