title: Symfony2 Unrecognized option "providers" under "security.providers.chain_provider"
body: <p>Guys i have this problem when trying to "php app/console doctrine:schema:update --force" i don't know how to solve it(Unrecognized option "providers" under "security.providers.chain_provider")</p>
  
  <p>this is my security.yml</p>
  
  <pre><code>security:
  
  role_hierarchy:
      ROLE_ADMIN:       ROLE_USER
      ROLE_SUPER_ADMIN: [ROLE_USER, ROLE_ADMIN, ROLE_ALLOWED_TO_SWITCH]
  
  encoders:
      Setsuna\PrivateBundle\Entity\User: sha512
  providers:
      in_memory:
          memory: ~
      fr3d_ldapbundle:
          id: fr3d_ldap.security.user.provider
      fos_userbundle:
          id: fos_user.user_manager
      chain_provider:
          providers: [fos_userbundle, fr3d_ldapbundle]
  
  firewalls:
      dev:
          pattern:  ^/(_(profiler|wdt)|css|images|js)/
          security: false
      main:
          pattern: ^/
          fr3d_ldap: ~
          form_login:
              provider: fos_userbundle
              csrf_provider: form.csrf_provider
              always_use_default_target_path: true
              default_target_path: /profile
          logout: true
          anonymous: true
  
  access_control:
      - { path: ^/login$, role: IS_AUTHENTICATED_ANONYMOUSLY }
  </code></pre>