fix start script and Dockerfile

mosquitto-start.sh

@@ -8,12 +8,12 @@ docker volume inspect $VOLUME > /dev/null || docker volume create $VOLUME
 docker pull $IMAGE
 
 docker run \
-  -it \
+  -d \
   --rm \
   -p1883:1883 \
   -v $VOLUME:/opt/etc/mosquitto \
   --link mariadb \
   --name mosquitto \
-  $IMAGE /bin/bash
+  $IMAGE