Added script to test issue 9, publish of a QoS2 message

tools_scripts/subscriber_client.groovy

@@ -51,10 +51,11 @@ class SubscriberCallback implements MqttCallback {
     }
 }
 
+String host = args[0]
 String tmpDir = System.getProperty("java.io.tmpdir")
 MqttDefaultFilePersistence dataStore = new MqttDefaultFilePersistence(tmpDir)
 
-MqttClient client = new MqttClient("tcp://localhost:1883", "SubscriberClient", dataStore)
+MqttClient client = new MqttClient("tcp://${host}:1883", "SubscriberClient", dataStore)
 def callback = new SubscriberCallback()
 client.callback = callback
 client.connect()