v2.0

Changes:

• Asynchronous

import PurgeCSS from "purgecss";

const purgecssResults = await new PurgeCSS().purge({
    // options
});

• Extractor is a function

content => content.match(/[\w-/:]+(?<!:)/g) || []

• variables option to remove unused CSS variables
• Drop support of NodeJS < 8