code: function formatFileName(filepath) {
  
          var validFilename;
  
          validFilename = filepath.replace(/\s/g, options.separator);
          validFilename = validFilename.replace(/[^a-zA-Z_0-9.]/, '');
          validFilename = validFilename.toLowerCase();
  
          return validFilename;
      }
docs: Format file name
  @param  {String} path
  @return {String}