Note about birthday domain logic
Adding failing end-to-end test for leap year birthday
Extract a unique person generator method in test
Creating a MonthAndDate object for birthday comparisons
PersonRegistry can now check multiple dates for matching.

This change is so that multiple dates can be checked for leap year birthdays.
Adding a calculator/strategy for determining what days to check for birthdays.
Notifying leap-day birthdays in non-leap-years.
Updating notes