Exchange: calendar sync window linked to email sync window

Email sync <= 2 weeks, Calendar sync = 2 weeks
Email sync = 1 month, Calendar sync = 1 month
Email sync all, Calendar sync all

Ported from: http://review.cyanogenmod.org/#/c/10836/

Change-Id: Ie68528218d993f9c550fe4f6ab44a75c7e9857f8