Ability to Configure Hydrator Filters

Adds the ability to configure filters for the hydrator:

```php
    // ...
    'doctrine-hydrator' => array(
        'Acme\\V1\\Rest\\User\\UserHydrator' => array (
            // ...
            'filters' => array(
                // a service...
                'Acme\\V1\\Rest\\Person\\PersonFilter',
                // .. or a lambda / anonymous function ...
                'optional_key' => function($field) {
                    return true; // will always exclude the field
                },
                // ... or an array
                array(
                    'filter'    => 'service' // or lambda,
                    'condition' => FilterComposite::CONDITION_AND, // default is OR
                ),
            ),
        ),
    ),
```

If this is interesting then I can throw a few more things in - e.g. a very easy way to exclude fields (by providing some built-in filters).