code: function runPngquant(args, callback) {
          grunt.log.debug('Trying to spawn "' + options.binary + '" with arguments: ');
          grunt.log.debug(args.join(' '));
          grunt.util.spawn({
              cmd: options.binary,
              args: args
          }, callback);
      }
docs: Runs pngquant binary
  @param  {Array}   args      Command line arguments
  @param  {Function} callback Callback