TRUNK-4389: Added DRUG_ORDER_TYPE_UUID & TEST_ORDER_TYPE_UUID constants to OrderType class,
Added unit test method saveOrder_shouldSetOrderTypeOfDrugOrderToDrugOrderIfNotSetAndConceptNotMapped to OrderServiceTest,
Added unit tests and code to set order type of drug/test order to drug/test order respectively if not set and concept not mapped in saveOrder() method

(cherry picked from commit cdb90e75c2fae11492fba94121c05ea3968143f5)