MDLSITE-3612 - support csslint checking of CSS

Since it reports in checkstyle format we can use existing reporting
mechanisms.
MDLSITE-3612 improve smurf.html display a bit

* Rearrange CSSlint ordering
* Reduce excess whitespace so it doenst need much scrolling
* Reduce size of headers
* Remove <hr> to seperate errors and warnings because it doesn't make
  as much sense with all the different sections on the page
* Add bold to the summary of error numbers - because I never noticed
  this summary was the totals for all sections before..
Merge pull request #27 from danpoltawski/MDLSITE-3612-csslint

MDLSITE-3612 - support csslint checking of CSS