Make sure we don't get a doctrine error message.

The old exception message gave us a lot of info about our application.
This could help a user find out we're running Symfony and find possible
exploits. This commit will hide the message behind a translated version
of the message of the exception.

Resources/views/Security/login.html.twig

@@ -13,7 +13,7 @@
 
  {% if error %}
  <div class="alert alert-info">
- {{ error|trans }}
+ {{ error.messageKey|trans(error.messageData, 'security') }}
  </div>
  {% endif %}