Bug 1078243 - [Costcontrol] When the Starting day of the reset period is...

... 31th, the app does not calculated correctly the end of the reset period.
Tricky, I would prefer to add some semantics here by encapsulating this into a meaningful function such as `setToPreviousMonthDate()` or maybe just for the `0` to `PREVIOUS_MONTH_LAST_DATE`.