Further simplifies CleanCSS#minify by extracting debug options.
Further simplifies CleanCSS#minify by extracting debug options.

GerHobbelt/clean-css,scottgonzalez/clean-css,shelsonjava/clean-css,HossainKhademian/CleanCss,webconnex/clean-css,stuht/clean-css,jakubpawlowicz/clean-css,yomed/clean-css,vlajos/clean-css,island205/clean-css,MartyIX/clean-css