Add EventManager in Router/Http/Part

@DASPRiD

Like always, sorry for my english.


I am trying to add translation in the url, and I want something like 

http://www.website.com/fr/contact-nous
http://www.website.com/en/contact-us

Router configuration :  
```php
array(
  'router' => array(
    'router_class' => 'Zend\Mvc\Router\Http\TranslatorAwareTreeRouteStack'
    'routes' => array(
         'i18n' => array(
                'type' => 'Segment',
                'options' => array(
                    'route' => '[/:lang]',
                    'defaults' => array(
                        'lang' => 'fr'
                    ),
                    'constraints' => array(
                        'lang' => 'fr|en'
                    )
                ),
                'may_terminate' => false,

                'child_routes' => array(
                    'home' => array(
                        'type' => 'Literal',
                        'options' => array(
                            'route' => '/',
                            'defaults' => array(
                                'controller' => 'App\Controller\Index',
                                'action' => 'index',
                            ),
                        ),
                    ),

                    'contact' => array(
                        'type' => 'Segment',
                        'options' => array(
                            'route' => '/{contact}',
                            'defaults' => array(
                                'controller' => 'App\Controller\Contact',
                                'action' => 'index',
                            ),
                        ),
                    )
                )
            )
    ),
  )
)
```

http://www.website.com/fr/contact-nous works , but not http://www.website.com/en/contact-us .

The issue is like egg and chicken.
I need to set the Route translator locale to the value of :lang , but the routing is still not finished, so I still don't know the lang requested.

Maybe create my own Route would work too but 
I think that adding an event manager in SimpleRouteStack ( for now, I only edited Part route) will make it easier.


All I have to do is add in Module
```php
 public function onBootstrap(EventInterface $e)
    {
        if (!($e instanceof MvcEvent)) {
            return;
        }

        $serviceLocator = $e->getApplication()->getServiceManager();

        $sharedManager = $e->getApplication()->getEventManager()->getSharedManager();
        $sharedManager->attach(
            'Zend\Mvc\Router\Http\Part',
            'match',
            function (EventInterface $event) use ($serviceLocator) {
                $match = $event->getParam('match');
                if ($match instanceof RouteMatch) {
                    if ($lang = $match->getParam('lang')) {
                        $serviceLocator->get('Translator')->setLocale($lang); 
                        $serviceLocator->get('Router')->setDefaultParam('lang', $lang); // don't need specify current lang on assemblage
                    }
                }
            }
        );
    }
```