Update sonata_template_box to allow translations

I've updated `sonata_template_box` Twig node to allow translations.

This is not a BC break, it continues to work as normal with current tags:

```jinja
{% sonata_template_box 'This is the gallery media block. Feel free to override' %}
```

and it can also take a translation key and a translation domain bundle name, like this:

```jinja
{% sonata_template_box 'sonata_template_box_media_gallery_block' 'SonataDemoBundle' %}
```

and this will translate using the current locale, below in french:

![capture decran 2014-02-04 a 13 30 12](https://f.cloud.github.com/assets/103900/2075963/22a9fce0-8d98-11e3-9479-865daa5d93b0.png)