message: add clean cache to apt install
diff: @@ -9,7 +9,8 @@ ENV IROHA_BUILD /opt/iroha/build
  RUN apt-get update && \
  apt-get -y --no-install-recommends install apt-utils software-properties-common wget gpg-agent; \
  - apt-get -y clean
  + apt-get -y clean && \
  + rm -rf /var/lib/apt/lists/*
  # add repos
  RUN set -e; \
  @@ -73,6 +74,7 @@ RUN set -e; \
  RUN set -e; \
  apt-get update; \
  apt-get -y install openjdk-8-jre; \
  + rm -rf /var/lib/apt/lists/*; \
  java -version
  # python bindings dependencies
  