Bugfix/webspace security

__Tasks:__

- [x] finish the code
- [x] test coverage
- [ ] gather feedback for my changes

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | yes https://github.com/sulu-cmf/SuluSecurityBundle/commit/8caa25a3f67be5d340fad595ac0b32cdf7c6900f
| New feature?  | no
| Tests pass?   | yes
| Fixed tickets | none
| Doc           | none