title: Why is my User Login no longer working after upgrading to Symfony3
body: <p>I came along a strange Problem with Symfony 3.
  Under Symfony 2 everyhting worked out of the Box (Login).
  But under Symfony 3 it doesn't validate at all.
  The Doctrine Layer is not Loading my User Object nor the Repository.</p>
  
  <p>Whats going on?</p>