Doctrine 2 bootstrap file (defining explicitly the AnnotationDriver) 
Entities should now import the Mapper Classes : 
use Doctrine\ORM\Mapping as ORM ;
/**
 * @ORM\Entity
 * @ORM\Table(name="blog")
 */
class Blog
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;