attempt to clean apt-get sourcelist

Dockerfile

@@ -7,6 +7,7 @@
 FROM ubuntu
 # File Author / Maintainer
 # MAINTAINER name Chunteng Xiao
+RUN apt-get clean
 RUN apt-get update
 RUN apt-get -f install -y nodejs nginx npm curl
 RUN curl --insecure -o ./sonarscanner.zip -L https://sonarsource.bintray.com/Distribution/sonar-scanner-cli/sonar-scanner-cli-3.2.0.1227-linux.zip