title: Symfony2 translation, parameter not working
body: <p>I'm having a problem with Symfony2's translator.</p>
  
  <p>I have a DateTimeFormatter class (simplified here):</p>
  
  <pre><code>&lt;?php
  
  namespace Project\CommonBundle\Util;
  
  use DateTime;
  use Symfony\Component\Translation\TranslatorInterface;
  
  class DateTimeFormatter
  {
      private $translator;
  
      public function __construct(TranslatorInterface $translator)
      {
          $this-&gt;translator = $translator;
      }
  
      public function format(DateTime $datetime, array $options = array())
      {
          $delta = time() - $datetime-&gt;getTimestamp();
  
          return $this-&gt;translator-&gt;trans('datetime_formatter.seconds_ago', array('%seconds%', $delta);
      }
  }
  </code></pre>
  
  <p>With translation file:</p>
  
  <pre><code>datetime_formatter:
      seconds_ago: %seconds% seconds ago
  </code></pre>
  
  <p>And I configured it as a service:</p>
  
  <pre><code>parameters:
      datetime_formatter.class: Skepin\CommonBundle\Util\DateTimeFormatter
  services:
      common.util.datetime_formatter:
              class: %datetime_formatter.class%
              arguments: [@translator]
  </code></pre>
  
  <p>The problem is: when I use it, the text displayed is <code>%seconds% seconds ago</code>, the parameter is not replaced. What am I missing?</p>
  
  <p>Thanks!</p>