WIP on paydate_frequency

- Created test case for paydate_frequency construction
- Implemented paydate_frequency constructor
- Implemented paydate_frequency deallocator
- Created test case for paydate_frequency ok validation
- Created test case for paydate_frequnecy fail validation
Completed paydate_frequency implementation

- Completed paydate_frequency validate failure tests
- Implemented paydate_frequency_validate method
- All tests pass