fix(mqtt binding Atos-Research-and-Innovation#65): correct handling o…

…f reconnections (Atos-Research-and-Innovation#67)

lib/bindings/mqttClient.js

@@ -58,6 +58,7 @@ class MqttClient {
         var options = {};
         options.username = this.username;
         options.password = this.password;
+        var connected = false;
 
         winston.info('Connecting to MQTT server %s with options:%s', host, JSON.stringify(options));
         this.mqttClient = mqtt.connect(
@@ -70,7 +71,10 @@ class MqttClient {
         this.mqttClient.on('message', this.listener);
         this.mqttClient.on('connect', function(object, binding) {
             winston.info('Connected to MQTT server');
-            return callback();
+            if (!connected) {
+                connected = true;
+                return callback();
+            }
         });
     }