code: function preen(options, callback) {
    
    preview = options.preview;
    verbose = options.verbose;
    directory = options.directory;
  
    if(preview || verbose){
      logger.transports.console.level = 'verbose';
    }
  
    try {
      bowerJSON = require(process.cwd()+'/'+bower.config.json);
    }
    catch(err) {
      logger.error('Error trying to read '+bower.config.json, err);
      return;
    }
  
    async.each(Object.keys(bowerJSON.preen), preenPackage, callback);
  }
docs: an optional argument to set a custom root directory (for processing after copying bower files)