Calculators: Self assessment penalty calculator - logic content update and bug fix

The previous version of the calculator had some discrepancies, in order to have the calculator working correctly they have been fixed. 

List of extra changes: 
https://docs.google.com/a/digital.cabinet-office.gov.uk/document/d/1jlIP6UO9uyGUYElSxZ84l5CabjJ2Too9OyDT0R0R8JY/edit

Story link:
https://www.pivotaltracker.com/story/show/64743742