Fixed issue #7882: Monday is now first day in calender (partial fix)

DEV: already done in master, see
https://github.com/LimeSurvey/LimeSurvey/pull/88
DEV: now the same in 2.05
Merge pull request #95 from mfaber/firstday205

Fixed issue #7882: Monday is now first day in calender (partial fix)