Since Composer 1.2, binaries are re-installed from vendors if there aren't found.
This avoid us to commit binaries vendors into the repo.
⚠️ You have to update your Composer to the 1.2 (`composer selfupdate`)
Having a big composer.lock on a final project can have side effect on incoming PR that add a new vendor.
Mostly because conflict are too frequent.
By ignoring composer.lock we ease the PR submission and rebase.
BUT we need to be careful when we release a new version of wallabag. We should manually `git add -f composer.lock` to update it.
Since composer.lock will no longer be commited I switch the `composer install` to a `composer up` in the travis configuration.
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 :))