authenticationToken is not recognized
I have the issue that mý authToken is not being recognized...

Tried several different methodes, checked the code but somewhere the linking between the plugin and the config seems to fail.

Here is the Failure message:
```
Load homebridge-eWeLink.eWeLink
[2017-12-26 05:58:12] [homebridge-eWeLink.eWeLink] Intialising eWeLink
/usr/local/lib/node_modules/homebridge-ewelink/index.js:42
    this.authenticationToken = config['authenticationToken'];
                                     ^

TypeError: Cannot read property 'authenticationToken' of null
    at new eWeLink (/usr/local/lib/node_modules/homebridge-ewelink/index.js:42:3             8)
    at Server._loadDynamicPlatforms (/usr/local/lib/node_modules/homebridge/lib/             server.js:325:30)
    at Server.run (/usr/local/lib/node_modules/homebridge/lib/server.js:87:8)
    at module.exports (/usr/local/lib/node_modules/homebridge/lib/cli.js:40:10)
    at Object.<anonymous> (/usr/local/lib/node_modules/homebridge/bin/homebridge             :17:22)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.runMain (module.js:604:10)
    at run (bootstrap_node.js:394:7)
    at startup (bootstrap_node.js:149:9)
    at bootstrap_node.js:509:3

```
and here is my config:

```
	"platforms": [{
			
		"platform": "eWeLink",
		"name": "eWeLink",
		"autheticationToken": "authToken is in here!",
		"apiHost": "eu-api.coolkit.cc:8080/api/group?apikey=apikeygoeshere&appid=xyz&nonce=eto149q7&ts=1514263532&version=6",
		"webSocketApi": "eu-api.coolkit.cc:8080/api/group?apikey=apikeygoeshere&appid=xyz&ts=1514263532&version=6"
		},
			]
}
```
greetings from Germany 

Kevin 