Little change Dockerfile

tools/Dockerfile

@@ -10,7 +10,7 @@ RUN apt-get update && apt-get install -yq python python-pip git vim tmux zip bui
 
 ## install composer
 ADD composer.sh /opt/composer.sh
-RUN chmod +x /opt/composer.sh ; ./opt/composer.sh
+RUN chmod +x /opt/composer.sh ; sh /opt/composer.sh
 
 ## install docker-composer
 #RUN curl -L https://github.com/docker/compose/releases/download/1.17.0/docker-compose-`uname -s`-`uname -m` -o /usr/local/bin/docker-compose