NZ Age at Death; logic changed, now includes Weeks

The logic for defaulting the New Zealand Age at Death has changed to the following:

If less than 1 week, "n day(s)"
If less than 1 month, "n week(s)"
If less than 1 year, "n month(s)"
otherwise "n year(s)"

where n=number, (s)= plural if number more than 1.

This is also carried over to the EDI export, where Weeks is now supported.