title: How to set expiration time to session in the controller?
body: <p>I need to set a session with expiration time of 5min in controller. How do i do it? 
  I need something like:</p>
  
  <pre><code>$this-&gt;container-&gt;get('session')-&gt;set('mysession', 'value', 'expiration');
  </code></pre>
  
  <p>in symfony2 way?</p>
  
  <p>Thanks!</p>