title: node-archiver: Archive multiple directories
body: <p>Is it possible to archive multiple directories when you know their paths? Let's say: <code>['/dir1','dir2', .., 'dirX']</code>. What I am doing now, is to copying directories in a single directory, let's say: <code>/dirToZip</code> and do the following:</p>
  
  <pre><code>var archive = archiver.create('zip', {});
  archive.on('error', function(err){
      throw err;
  });
  archive.directory('/dirToZip','').finalize(); 
  </code></pre>
  
  <p>Is there an approach to append directories into the archive and not with a specific pattern that bulk requires? Thanks in advance!</p>