styleguide absolute path issue fix

styleguide.js

// origin source: https://github.com/indieisaconcept/grunt-styleguide/blob/master/tasks/styleguide.js#L221

styleguide.files = {
    file: file,
    src: files.length > 0 && files || grunt.file.exists(file.orig.src) && file.orig.src,
    dest: file.dest
};

styleguide.files.base = (function () {
  var base;
  if (files.length) {
    // note that it define the base path based only on the first existent path
    if (grunt.file.isPathAbsolute(files[0])) {
      base = path.dirname(files[0]);
    } else {
      base = helper.findBasePath(files) || './';
    }
  }
  return base || './';
}());