+ odering test

1) Should make sure the `README.md` example test works ;)
2) What should happen when there is an overriding CSS rule?
  * ordering-expected.css = with no reduction; ensure the overriding rule is left at later position
  * ordering-optimal.css = smarter node-css-mqpacker that removes unneeded CSS styles

This is more to open discussion.  But perhaps this PR can test solution.
TIA