title: Add php code in Gantry 5 template header
body: <p>I am using Gantry 5 template and I want to add php code in the header. I set some variables using php and access them in the script tag. For example</p>
  
  <pre><code>&lt;?php
      $id = $user-&gt;id;
      $name = $user-&gt;username;
  ?&gt;
  &lt;script&gt;
      var id = '&lt;?php echo $id; ?&gt;';
      var name = '&lt;?php echo $name; ?&gt;';
  &lt;/script&gt;
  </code></pre>
  
  <p>I want to add the above code in head of Gantry 5 template. In we just add the code in index.php but this mechanism is different in Gantry 5. How this code can be added?</p>