Custom url for pages based on routes

# PR for issue #158
An alternative to query params

## Usage

### config.yml

```yml
knp_paginator:
    template:
        pagination: KnpPaginatorBundle:Pagination:twitter_bootstrap_pagination_route.html.twig
```

### Controller

```php
    /**
    * @Route("/", name="acme_demo")
    * @Route("/page/{page}/", name="acme_demo_paginator")
    * @Template()
    */
    public function indexAction($page = 1)
    {
        $em    = $this->get('doctrine.orm.entity_manager');
        $dql   = "SELECT a FROM AcmeDemoBundle:Article a";
        $query = $em->createQuery($dql);
        $pagination = $paginator->paginate(
            $query,
            $page /*page number*/,
            10/*limit per page*/
        );

        return array(
            'pagination' => $pagination 
        );
    }
```

### View

```jinja
<div class="navigation">
    {{ knp_pagination_render(pagination, null, {}, {'firstPageRoute': 'acme_demo', 'otherPagesRoute': 'acme_demo_paginator'}) }}
</div>
```

**Note:** If you want to set routes in controller, there is an alternative:
```php
$pagintion->setFirstPageRoute('acme_demo');
$pagintion->setOtherPagesRoute('cme_demo_paginator');
```