[FEATURE] added configuration and translations for additional contact fields

__Tasks:__
- [x] add configuration for additional fields in contact
- [x] add translations for additional fields in contact
- [ ] gather feedback for my changes

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | no --> unknown configuration needs https://github.com/sulu-cmf/SuluContactBundle/pull/88
| Fixed tickets | none
| Doc           | none