update license attribute
update license attribute

Type and url are now depreciated

http://npm1k.org/
https://docs.npmjs.com/files/package.json#license

(#102)

LoicMahieu/gulp-minify-css,keremciu/gulp-minify-css,HaNdTriX/gulp-minify-css,MichaelFBA/gulp-minify-css,zarko-tg/gulp-minify-css,sibrus/gulp-minify-css