3. Add PHPCR-ODM documents for rooms and presentations

We now add a couple of documents and fixtures for Room and Presentation. We don't have any navigation yet, but going to http://conf.lo/app_dev.php/rooms/copernicus will display a room page and http://conf.lo/app_dev.php/rooms/copernicus/diving-deep-into-twig will show the twig talk page. As we did not configure a specific template, the pages do not show their specific information yet.