message: use docker image "rwthos/hermitcore-rs" for our tests
diff: -# Download base image ubuntu 18.04
  -FROM ubuntu:18.04
  +FROM rwthos/hermitcore-rs:latest
  ENV DEBIAN_FRONTEND=noninteractive
  # Update Software repository
  +RUN apt-get clean
  RUN apt-get -qq update
  -# Install required packets from ubuntu repository
  -RUN apt-get install -y apt-transport-https curl wget vim nano git binutils autoconf automake make cmake qemu-kvm qemu-system-x86 nasm gcc g++ build-essential libtool bsdmainutils
  -RUN apt-get install -y libssl-dev pkg-config zlib1g-dev
  +RUN PATH="/opt/hermit/bin:/root/.cargo/bin:${PATH}" /root/.cargo/bin/cargo install cargo-xbuild
  +RUN PATH="/opt/hermit/bin:/root/.cargo/bin:${PATH}" /root/.cargo/bin/cargo install --git https://github.com/hermitcore/pci_ids_parser.git
  -# add path to hermitcore packets
  -RUN echo "deb [trusted=yes] https://dl.bintray.com/hermitcore/ubuntu bionic main" | tee -a /etc/apt/sources.list
  +ENV XARGO_RUST_SRC="/root/.cargo/lib/rustlib/src/rust/src/"
  -# Update Software repository
  -RUN apt-get -qq update
  -
  -# Install required packets from ubuntu repository
  -RUN apt-get install -y --allow-unauthenticated binutils-hermit newlib-hermit-rs pte-hermit-rs gcc-hermit-rs libhermit-rs libomp-hermit-rs
  -
  -# Install Rust toolchain
  -RUN curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain nightly
  -RUN /root/.cargo/bin/cargo install cargo-xbuild
  -RUN /root/.cargo/bin/rustup component add rust-src
  -RUN /root/.cargo/bin/cargo install --git https://github.com/hermitcore/pci_ids_parser.git
  +# Switch back to dialog for any ad-hoc use of apt-get
  +ENV DEBIAN_FRONTEND=dialog
  -ENV PATH="/opt/hermit/bin:/root/.cargo/bin:${PATH}"
  -ENV EDITOR=vim
  