[FEATURE] Implemented extract format

__Tasks:__

- [x] test coverage
- [ ] gather feedback for my changes


__Informations:__

| Q             | A
| ------------- | ---
| Tests pass?   | yes
| Fixed tickets | none
| BC Breaks     | none
| Doc           | none
If the format is html, there should be a redirect to the page without the file extension, so http://sulu-standard.lo/de/uebersicht.html should redirect with a status code of 301 to http://sulu-standard.lo/de/uebersicht /cc @crashOverride