code: function readCss () {
    return new Promise(function(resolve, reject){
      readFile(SRC, {encoding: 'utf8'}, function(err, str){
        if (err) { return reject(err); }
        resolve(str)
      });
    });
  }
docs: Read local github's css
  @private
  @return {Promise} - resolves to a {String} with the local github's css