Boot Failure
I'm seeing a similar error to several others when trying to boot `homebridge` with `homebridge-smartthings` for the first time. Here's my boot trace:

```
[2018-1-6 18:38:07] Loaded plugin: homebridge-server
[2018-1-6 18:38:07] Registering platform 'homebridge-server.Server'
[2018-1-6 18:38:07] ---
[2018-1-6 18:38:08] Loaded plugin: homebridge-smartthings
[2018-1-6 18:38:08] Registering platform 'homebridge-smartthings.SmartThings'
[2018-1-6 18:38:08] ---
[2018-1-6 18:38:08] Loaded config.json with 0 accessories and 2 platforms.
[2018-1-6 18:38:08] ---
[2018-1-6 18:38:08] Loading 2 platforms...
[2018-1-6 18:38:08] [SmartThings] Initializing homebridge-smartthings.SmartThings platform...
[2018-1-6 18:38:08] [SmartThings] Fetching Smart Things devices.
[2018-1-6 18:38:08] [Homebridge Server] Initializing Server platform...
[2018-1-6 18:38:08] [Homebridge Server] is listening on: http://192.168.1.37:8765
[2018-1-6 18:38:08] [SmartThings] Error received type undefined - undefined
[2018-1-6 18:38:08] [SmartThings] Unknown Capabilities: []
```

Checking in Live Logging in smart things, I see nothing when booting smart things, and what looks like success when configuring the Complete JSON API in the app.

One thing I did notice is that when I set a the list of devices (_'Configure Devices'_), although the list does seem to save (looking at the live logging) it's wlawys blank again when I go back into the configuration UI in the app.

My configuration looks like this:

```json
{
    "bridge": {
        "name": "Homebridge",
        "username": "CC:22:3D:E3:CE:30",
        "port": 51563,
        "pin": "031-45-154"
    },

    "platforms": [
        {
            "platform" : "homebridge-smartthings.SmartThings",
            "name": "SmartThings",
            "app_url": "https://graph.api.smartthings.com:443/api/smartapps/installations/",
            "app_id": "<REDACTED BUT VERIFIED AS OAuth/Client-Id FROM SETTINGS>",
            "access_token": "<REDACTED BUT VERIFIED AS OAuth/Client-Secret FROM SETTINGS>",
            "polling_seconds": 3600,
            "update_method": "direct",
            "api_seconds": 30
        },
        {
            "platform": "Server",
            "port"    : 8765,
            "name"    : "Homebridge Server",
            "log"     : "/var/log/homebridge.log",
            "restart" : "sudo reboot"
        }
    ]
}
```

What can I try to get things going?