[FEATURE] outsourced header functions to use them in other bundles as well

__Tasks:__
- [x] test coverage
- [ ] gather feedback for my changes

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | yes
| Fixed tickets | none
| Doc           | none

merge https://github.com/sulu-cmf/SuluAdminBundle/pull/109 before this PR