Add apt-get clean to Dockerfile

Author: SteveLTN

Dockerfile

@@ -10,7 +10,8 @@ RUN rm /var/log/nginx/access.log && \
 
 WORKDIR /root
 
-RUN apt-get update && \
+RUN apt-get clean && \
+    apt-get update && \
     apt-get install -y python ruby cron iproute2 apache2-utils logrotate wget inotify-tools && \
     apt-get clean && \
     rm -rf /var/lib/apt/lists/*