So they can be installed using the `assets:install` command and there'll no longer symlink in the repo
They moved from `web/themes/...` to `bundles/wallabagcore/themes/...`
Re-defined the config / user relation to be OneToOne bidirectionnal.
ConfigType is now a service so I can inject the list of available themes that are also used by LiipThemeBundle
Force sqlite for test
In case of people use a different driver in parameter.yml (yes I do :))