fix css module ordering
fix css module ordering

extract-text-webpack-plugin had this bug: http://bit.ly/2ueFvXt
and was fixed with: http://bit.ly/2hCkpOf
So I borrowed the odering code from there and applied it to this
plugin to fix ordering.

faceyspacey/extract-css-chunks-webpack-plugin,faceyspacey/extract-css-chunks-webpack-plugin,brightbytes/extract-css-chunks-webpack-plugin,brightbytes/extract-css-chunks-webpack-plugin