Update test for media rule
Fix broken media query test by using cssutils for pasing CSS
Remove unused variables
Fix media query rules are not left in style tag issue
Merge pull request #53 from victorlin/bugfix-media-query

* bugfix-media-query:
  Fix media query rules are not left in style tag issue
  Remove unused variables
  Fix broken media query test by using cssutils for pasing CSS
  Update test for media rule