enable MQTT in RabbitMQ

Dockerfile.broker

+FROM rabbitmq:management
+RUN rabbitmq-plugins enable --offline rabbitmq_mqtt
\ No newline at end of file

docker-compose.yml

@@ -80,13 +80,16 @@ services:
 
   # AMQP broker for VILLAScontroller
   broker:
-    image: rabbitmq:management
+    build:
+      context: .
+      dockerfile: Dockerfile.broker
     environment:
       RABBITMQ_DEFAULT_USER: "villas"
       RABBITMQ_DEFAULT_PASS: "s3c0sim4!"
     ports:
       - "8083:15672"
       - "5672:5672"
+      - "1883:1883"
     restart: always
 
   # A VILLAScontroller for creating some dummy simulators