FSi Removable File Type

@fsi-open code review please
tak bym sformatowal
```
$builder->add( 'file',  'file', array(
    'mapped' => true,
    'required' => $options['required'],
    'data_class' => 'FSi\DoctrineExtensions\Uploadable\File',
    'property_path' => $options['property_path'],
    'label' => false
));
```