Allow multiple route match

Patch gives an ability to inject multiple assets on a single route.
``` php
return array(
    'assetic_configuration' => array(
        'routes' => array(
            // make sure base assets are on the topmost position
            'routes' => array(
                '(?!admin).*' => array(
                    -100 => '@base_css',
                    -90  => '@base_js',
                )
            ),
        )
    )
);
```
In the following example assets will be applied to all routes but admin and will be placed in the topmost position inside head tag.