Various fixes for tutorial

Symfony\Cmf\Bundle\RoutingBundle\Doctrine\Phpcr\Route::setRouteContent() not defined, use setContent() instead
For Symfony\Cmf\Bundle\ContentBundle\Doctrine\Phpcr\StaticContent, title and body are not nullable
i think php is the default type of blocks, so you should just do `... modify it as follows::` and then start  the php code below. no need for the opening `<?php`