Partial deprecation warning

Fix this warning : 

```
DEPRECATION WARNING: Passing the format in the template name is deprecated. Please pass render with :formats => [:html] instead. (called from _app_views_layouts_application_html_haml__2515002154092969009_70295921967440 at /data/Projets/voxe-web/app/views/layouts/application.html.haml:16)
```