[Component] Addressing

Replaces #576.

Argh... Do not merge yet please, there is a fatal error, and I don't know why. If somebody has an idea...

``` 
 [Doctrine\ORM\Mapping\MappingException]                                                                                                  
  The target-entity Sylius\Bundle\AddressingBundle\Model\Address cannot be found in 'Sylius\Bundle\CoreBundle\Model\User#billingAddress'. 
```

Edited by @jjanvier to set the original comment