support CPS (pre-2013) pension scheme
Created by: rjw57
Add CPS pre-2013 employee and employer rates along with a test that it matches the table on the HR website.
Closes #6 (closed)
Created by: rjw57
Add CPS pre-2013 employee and employer rates along with a test that it matches the table on the HR website.
Closes #6 (closed)