Add Dockerfile for build system.

docker/Dockerfile

@@ -0,0 +1,31 @@
+FROM ubuntu:17.04
+
+ENV REDOX_TOOLCHAIN_APT http://static.redox-os.org/toolchain/apt/
+ENV SRC_PATH /src
+ENV CARGO_HOME /cargo
+ENV RUSTUP_HOME /rustup
+ENV PATH $CARGO_HOME/bin:$PATH
+
+RUN apt-get update \
+      && apt-get install -y git gosu gcc fuse nasm qemu-utils pkg-config \
+         libfuse-dev make curl file sudo apt-transport-https \
+      && mkdir -p $CARGO_HOME \
+      && mkdir -p $RUSTUP_HOME \
+      && curl https://sh.rustup.rs > sh.rustup.rs \
+      && sh sh.rustup.rs -y \
+      && rustup update \
+      && rustup component add rust-src \
+      && rustup default nightly \
+      && echo "deb $REDOX_TOOLCHAIN_APT /" >> /etc/apt/sources.list.d/redox.list \
+      && apt-get update \
+      && apt-get install -y --force-yes x86-64-elf-redox-newlib x86-64-elf-redox-binutils x86-64-elf-redox-gcc \
+      && cargo install xargo \
+      && mkdir -p "$SRC_PATH"
+
+WORKDIR $SRC_PATH
+
+COPY entrypoint.sh /usr/local/bin/entrypoint.sh
+
+RUN chmod +x /usr/local/bin/entrypoint.sh
+
+ENTRYPOINT ["/usr/local/bin/entrypoint.sh"]