fixed duplication bug with trailing slash in url

Removed the trailing slash from the startpage, which results now in a 404 error.

__Tasks:__

- [ ] test coverage
- [ ] gather feedback for my changes


__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| Tests pass?   | yes
| Fixed tickets | none
| Doc           | none