bugfix for #42
add attr 'infinite'
fix a typo
Add `currentColor` color keyword

Seealso: http://www.w3.org/TR/css3-color/#currentcolor
Merge pull request #43 from hail2u/currentcolor

Add `currentColor` color keyword
Add max/min support for aspect-ratios
Make max/min prefixes optional
Merge pull request #44 from cakebaker/fix_max_min_aspect_ratio

Add max/min support for aspect-ratios
Fix typo (mulitple -> multiple)
Merge pull request #45 from cakebaker/fix_typo

Fix typo (mulitple -> multiple)