[WIP] Feature/header

refactoring of event names because of new header

__Tasks:__

- [ ] refactor eventnames
- [ ] gather feedback for my changes

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | none
| Fixed tickets | none
| Doc           | none

__Merge before this PR:__
https://github.com/sulu-cmf/SuluAdminBundle/pull/98