dt - add year selector to mobile version.
@bug W-1902509@

Conflicts:

	aura-components/src/main/components/ui/datePicker/datePicker.css
	aura-components/src/main/components/ui/datePicker/datePickerHelper.js
Put a workaround on year selection change issue.
@bug W-1903593@
datePicker - workaround for the covered "set" link on iPad.
Merging origin/ssun/master-pending-merge186patch into master