title: Implement change password in Symfony2
body: <p>What is the best way to implement change password functionality in Symfony2? 
  Right now I'm using this:</p>
  
  <pre><code>$builder-&gt;add('password', 'repeated', array(
      'first_name' =&gt; 'New password',
      'second_name' =&gt; 'Confirm new password',
      'type' =&gt; 'password'
  ));
  </code></pre>
  
  <p>It should also contain the current password check for security reasons.</p>
  
  <p><strong>Note</strong>: I'm not using <code>FOSUserBundle</code>.</p>