Remove unnecessary options in VDateRange usage for roadblocks.
POST_edit_campaign respects business days.

This makes the validator consistent with the logic used in
PromoteLinkForm.
VDate: rework to use earliest and latest rather than future and past.

More flexible and easier to understand.
VDateRange better separates start and end dates.
Move error_fields into datepicker.
PromoteLinkForm: separate start and end date.
min_promote_future is an int.
Future date limit on creating campaigns.