[LazyRouteCollection] Missing argument for getRoutesByNames method fixed

I have noticed that [LazyRouteCollection.php#L50](https://github.com/symfony-cmf/Routing/blob/master/LazyRouteCollection.php#L50) is calling `getRoutesByNames` method on [RouteProviderInterface](https://github.com/symfony-cmf/Routing/blob/master/RouteProviderInterface.php) without any arguments. 

As method expects at least a name arg, php throws a missing argument error.

According to RouteProviderInterface:

> If $names is null, this method SHOULD return a collection of all routes
> known to this provider.
Merge pull request #92 from eymengunay/patch-2

[LazyRouteCollection] Missing argument for getRoutesByNames method fixed