Fixed MRR column header bug
User should be able to switch from "MRR" to "ARR" / "Revenue" or whatever column header one wants to use. It was previously hardcoded in one of the functions, now it just reads whatever the text is in the column headers (for the "Months" column too)
Stack Overflow resource: https://stackoverflow.com/a/35722367
Stack Overflow resource: https://stackoverflow.com/a/35722367