TRUNK-4133 - Implement discontinueOrder API in OrderService.

TRUNK-4133 - Modify OrderService.saveOrder(Order order) to correctly handle discontinue orders

Minor documentation change

TRUNK-4133 - Ensure discontinue and discontinued orders have the same concept

TRUNK-4133 - Changes based on review comments.
Add annotations for junit tests.
Some extra documentation.
Remove unnecessary executeDataset calls in OrderServiceTest
Make concept for discontinuation a normal concept, not a numeric
Additional assert statements