Feature/import-test

- [x] implement tests for import
- [x] import mappings with a file
- [x] test import mappings over file
- [x] fix url - contact relation

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- [x] use url_data event in datagrid for getting different types over 'type' GET parameter

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- [ ] gather feedback for my changes
- [x] test coverage


| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| Tests pass?   | yes
| Fixed tickets | none
| Doc           | none