Add markdown readme and fix rpath
specify the rpath variable to point to libmurefimpl2.so at compile time
add location of dynamic library libmurefimpl2.so to rpath within the stack.yaml file. This means that one no longer needs the LD_LIBRARY_PATH to be specified when running anuhc-exe through stack. The change is aimed at linux distro's, however a comment was added to allow osx and windows users to use the rpath as well.