[FEATURE] added responsible persons for accounts

added responsible persons for accounts

__Tasks:__

- [ ] gather feedback for my changes

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | none
| Fixed tickets | none
| Doc           | none

__Requires:__
- https://github.com/sulu-cmf/SuluSecurityBundle/pull/67
@michaelzangerle is this relation needed?