adjust to changed configuration format of seo bundle

| Q             | A
| ------------- | ---
| Bug fix?      | [yes|no]
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | adjust to https://github.com/symfony-cmf/SeoBundle/pull/163
| License       | MIT
| Doc PR        | -