Importer refactor

Merge of first round of importer refactorings with @motasem-salem work effectively merging #140 and #149.
This is something motasem did and you commented on in code review. I went to fix it but it breaks a lot of tests because it can't be false if the father doesn't have a data_of_birth and so on. So I thought that might be an issue for another refactor unless you feel strongly about it.
I can put a TO DO refactor message in there in the meantime.