Initial Dockerfile (#97)

* Initial Dockerfile

Dockerfile supports clang-8 and adds `iwasm` to `bin`.

* Updated README with Docker instructions

Added to Platform and app building section how to use the docker file to build the core and compile an app with clang.

Dockerfile

@@ -0,0 +1,21 @@
+# Currently supports clang-8 compiler
+# Using the "test.c" app from the README.md:
+# clang-8 --target=wasm32 -O3 -Wl,--initial-memory=131072,--allow-undefined,--export=main,--no-threads,--strip-all,--no-entry -nostdlib -o test.wasm test.c
+# Pay attention to spacing above! ^
+# iwasm test.wasm
+
+FROM ubuntu:latest
+
+RUN apt-get update && \
+  apt-get -y upgrade && \
+  apt-get install -y build-essential clang-8 cmake g++-multilib git lib32gcc-5-dev llvm-8 lld-8 nano
+
+WORKDIR /root
+
+RUN git clone https://github.com/intel/wasm-micro-runtime
+
+RUN cd wasm-micro-runtime/core/iwasm/products/linux/ && mkdir build && \
+  cd build && cmake .. && make
+
+RUN cd /usr/bin && ln -s wasm-ld-8 wasm-ld
+RUN cd /usr/bin && ln -s ~/wasm-micro-runtime/core/iwasm/products/linux/build/iwasm iwasm