1. Add CMF bundles and minimal configuration for the CMF

In this branch, we start using Doctrine PHPCR-ODM and the CMF bundles. To set up the repository, you need to run the following commands (after running `composer install` and making sure you configured a good Doctrine DBAL connection):

    php app/console doctrine:database:create
    php app/console doctrine:phpcr:init:dbal
    php app/console doctrine:phpcr:repository:init

## Notes

* I chose jackalope-doctrine-dbal as PHPCR implementation. See the [PHPCR website](http://phpcr.github.io/) for alternatives.
* The LiipDoctrineCacheBundle is not strictly needed, but will improve performance with jackalope-doctrine-dbal. If you use a different PHPCR implementation, you don't need the LiipDoctrineCacheBundle.
* I did not add any editing tools or fixtures yet. The site is still empty. Content fixtures and then editing will follow later.