create Blog class model with non-persisting property
adds a new comment object to the blog's comments member
run in console 'php app/console doctrine:generate:entities AcmeBlogBundle'
run in console 'php app/console doctrine:database:create' and 'php app/console doctrine:schema:create'
match show blog route only when the parameter id contains an integer
create functionality for show a blog
register DoctrineFixturesBundle in the kernel located at app/appKernel.php
create fixture to populate database and run in console 'php app/console doctrine:fixtures:load'
use Doctrine 2 to setup created and modified properties each time one blog is saved or updated