SA - Minimum wage calculator bug fix

historical_adjustment method wasn't historical at all, hence, the adjustment was calculated using present Minimum Wage rate. 

This is a change in the calculator that involved changing many tests, the bug was spread all around the SA and the fact that has been spotted in only one instance is a bit worrying. For this reason, I decided to create v2 files.

https://www.agileplannerapp.com/boards/105200/cards/6171