message: Docker fixes, and use Ubuntu 18.04
diff: FROM eosio/builder as builder
  ARG branch=master
  -RUN git clone -b $branch --depth 1 https://github.com/EOSIO/eos.git --recursive \
  +RUN git clone -b $branch https://github.com/EOSIO/eos.git --recursive \
  && cd eos && echo "$branch:$(git rev-parse HEAD)" > /etc/eosio-version \
  && cmake -H. -B"/tmp/build" -GNinja -DCMAKE_BUILD_TYPE=Release -DWASM_ROOT=/opt/wasm -DCMAKE_CXX_COMPILER=clang++ \
  -DCMAKE_C_COMPILER=clang -DCMAKE_INSTALL_PREFIX=/tmp/build -DSecp256k1_ROOT_DIR=/usr/local -DBUILD_MONGO_DB_PLUGIN=true \
  && cmake --build /tmp/build --target install
  -FROM ubuntu:16.04
  +FROM ubuntu:18.04
  RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get -y install openssl && rm -rf /var/lib/apt/lists/*
  COPY --from=builder /usr/local/lib/* /usr/local/lib/
  @@ -16,7 +16,7 @@ COPY --from=builder /tmp/build/bin /opt/eosio/bin
  COPY --from=builder /tmp/build/contracts /contracts
  COPY --from=builder /eos/Docker/config.ini /
  COPY --from=builder /etc/eosio-version /etc
  -COPY nodeosd.sh /opt/eosio/bin/nodeosd.sh
  +COPY --from=builder /eos/Docker/nodeosd.sh /opt/eosio/bin/nodeosd.sh
  ENV EOSIO_ROOT=/opt/eosio
  RUN chmod +x /opt/eosio/bin/nodeosd.sh
  ENV LD_LIBRARY_PATH /usr/local/lib
  