Adding father_alive field to importer and fixtures

Jira story: https://osraav.atlassian.net/browse/OSRA-221

Jira tasks:
OSRA-224#Code-Review
OSRA-226#Code-Review

- Added father_alive to pending_orphan model
- Added father_alive column to importer yaml settings
- Updated fixture files to new format
- Added validation for father_alive, father_is_martyr and father_date_of_death values
Especially if it's going to be reused by other models, extracting all this into a custom validator sounds like a terrific idea.