Rewrite Dockerfile again to be much smaller
Rewrite Dockerfile again to be much smaller

Docker stacks based Dockerfile was over 6g, making it really large.
This takes quite a long time to build on user's computers. The
newer one is simpler & is only 1g, much faster to build.

maojrs/riemann_book,maojrs/riemann_book,maojrs/riemann_book