TRUNK-4217 | Order Validations -

1) durationUnits can not be null if duration is present.
2) quantityUnits,doseUnits or durationUnits should be of type Units of Measure class
3) startDate should not be before encounter's encounterDateTime.
4) if scheduledDate is set, urgency should be ON_SCHEDULED_DATE.
5) order.orderType.javaClass should match order.class, subclasses