[BUGFIX] import: parental relations

__Tasks:__
- [x] adapted import for parent relation;
- [x] added fields api for account-contact
- [x] gather feedback for my changes 

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | yes
| Tests pass?   | none
| Fixed tickets | [none]
| Doc           | none