In this commit, the first weekday is set for week-header & week-grid.
The issue is, the first weekday is being set only for week-view,
resulting in incorrect display of weekdays in the week-header.
To fix this, the first weekday for week-header & week-grid is set
along with that of week-view.
https://bugzilla.gnome.org/show_bug.cgi?id=779346
