[WIP] ACLs activated by default to support best practice for Symfony's cache/log dir permissions issue

The best practice (by Symfony) to avoid the file permissions issue for directories `app/cache/` and `app/logs/` is to use utility `setfacl` in Ubuntu (see http://symfony.com/doc/current/book/installation.html#configuration-and-setup section "2. Using Acl on a system that does not support chmod +a" in the box "Setting up Permissions")

For that you have to install the `acl` utilities and adapt your `/etc/fstab` (see https://help.ubuntu.com/community/FilePermissionsACLs). Can we do that for the Symfony appliance? And how? (I am not familiar with TurnKey appliance development, the `/ect/fstab` I added as an overlay is just exemplary.)