Remove sass 3.3 dependency notice in README
Remove sass 3.3 dependency notice in README

danhart/flat-ui-sass,rwu1997/flat-ui-sass,danhart/flat-ui-sass,juliomoreira/flat-ui-sass,reyesyang/flat-ui-sass,juliomoreira/flat-ui-sass,DaRizat/flat-ui-sass,reyesyang/flat-ui-sass,rwu1997/flat-ui-sass,DaRizat/flat-ui-sass,wingrunr21/flat-ui-sass