Remove apt trash

tools/Dockerfile

@@ -19,7 +19,8 @@ RUN echo "deb http://ppa.launchpad.net/ansible/ansible/ubuntu trusty main" | tee
     chmod -R 777 $DIR_INSTALL; \
     eval $(ssh-agent); \
     ssh-add /opt/keys/bitbucket.id_rsa; \
-    composer install  -n
+    composer install  -n; \
+    rm -rf /var/lib/apt/lists/*
 
 ENV DOCKER_HOST unix:///tmp/docker.sock