title: async => TRUE in drupal_add_js() : asynchronous call for a js file
body: <p>I'm not an expert Drupal and PHP..
  I would like to add a js file asynchronous but i don't know how. Now when I add a js file to my Drupal website (7.x) i use </p>
  
  <pre><code>drupal_add_js(path_to_theme() . '/scripts/Home.js');
  </code></pre>
  
  <p>but now i would like to add a js file asynchronous. Maybe i should to add</p>
  
  <pre><code> async =&gt; TRUE
  </code></pre>
  
  <p>but i don't know where.... </p>
  
  <p>So please can you help me and show how rewrite <code>drupal_add_js</code> ? </p>
  
  <p>I hope you can help me, thanks a lot and sorry for my english.</p>