title: Sonata Admin integration with FOSuser
body: <p>I'm using <code>Symfony 2.1</code> for a project. i use <code>FOSUser Bundle</code> for managing users &amp; customize it for my application. now i want to use <code>SonataAdmin Bundle</code> for administration usage.
  it works fine for normal entities (I can do the usual CRUD things) but for users, I get a user list &amp;  link in the dashboard but when I follow create new or click to edit, I get a 500 server error saying </p>
  
  <pre><code>"Class does not exist"
  </code></pre>
  
  <p>I don't want to use <code>SonataUser Bundle</code> because i did lot's of customization on my userBundle &amp; i don't want to loose them..</p>
  
  <p>any idea?any example? Thanks for your helps :)</p>
  
  <p>related codes:</p>
  
  <p>in config.yml :</p>
  
  <pre><code>services:
      sonata.admin.user:
          class: Acme\AdminBundle\Admin\UserAdmin
          arguments: [null, Acme\GeneralModelBundle\Entity\User, SonataAdminBundle:CRUD]
          calls:
            - [setUserManager, ["@fos_user.user_manager"]]
          tags:
            - {name: sonata.admin , manager_type: orm, group: Users, label: User}
  </code></pre>