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
@nik :+1 for the explanation on why it needs to be in the db. I was going to reply with something similar to @theB264.

I started with a plan to write a custom validator that takes these 3 attributes (father_alive, father_is_martyr & father_date_of_death) and validates their value combination. But then I thought it might be better to use existing one-liner validations. This is the result (which I didn't like much). I submitted it to get your feedback.

I can take all of that out and have a custom validator which will be later used by pending_orphan and importer as well. What do you guys think?