Workfront Schedule Exceptions

Add function to API to add nonWorkDay (NONWKD) without needing to nest beneath an object with all other nonWorkDays.

Right now to add a nonWorkDay to a schedule all existing nonWorkDays must be collected first as an array. Then the array must be added to with new dates to an edit call on the parent object. The longer the schedule is used the larger this array becomes the harder it is to confirm no errors or missed dates.