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
Doesn't `inclusion: { in: [false] }` automatically handle `exclusion: { in: [anything else] }`?
Would `exclusion: { in: [nil] }` not be better done with `presence: true`?
Overall, I agree with the awkwardness - perhaps everything related to father's status would be better handled by a custom validator(s).
@theB264: I think it needs to be in the db to ensure record validity: if date of death is not recorded, does that mean that it's missing or that the father is alive? It seems that OSRA do not operate under the assumption that the date of death can be unknown. I would also prefer clarity over conciseness in the validation.