Manage Faq categories with Doctrine.
Cleanup the Faq model for categories with doctrine.
Handle Faq Questions and Categories with doctrine.

Todo:

 - Feedback
 - Frontend
 - Tags
Share session between environments.

This makes sure we can share sesssions between the installer and the
other environments.
Install Fork in dev/prod environment.

This change makes sure the parameters.yml file is created in one step,
and the real installation is done in the next step. This makes sure we
don't have to create the database and doctrine service manually.
Fix some issues with the Faq installer.
Make the Faq installer more error proof.
Less duplicate code in the ContentBlocks model.
Add a meta entity.

I've named the table "MetaDoctrine" for now, to be able to test Fork
containing the old meta table again. Doctrine changes the lowercased
meta table with the data for the Doctrine managed version if we don't
give it a custom name.

This should be changed later on.
Couple Faq categories and questions to the meta entity.
Save meta linked with Faq in a table managed by Doctrine.
Use Doctrin in the getUrl methods.
Make methods reusable in the frontend.