fix for retina-image mixin not parsing
fix for retina-image mixin not parsing

fix for less compiler as proposed on
https://github.com/imulus/retinajs/issues/56
YaroslavShapoval/shabo,thatgibbyguy/kube,harrykiselev/kube,imperavi/kube,stanwmusic/kube,YaroslavShapoval/shabo,flossy/kube-scss,tranc99/kube,igorgoroshit/kube,Dionid/shabo,Dionid/shabo,Dionid/shabo,Klaudit/kube,imperavi/kube