TRUNK-4392 Correct setting concept on drug order
TRUNK-4392 Added nullsafe check
TRUNK-4389: Added DRUG_ORDER_TYPE_UUID & TEST_ORDER_TYPE_UUID constants to OrderType class

TRUNK-4389: Added unit test methdo saveOrder_shouldSetOrderTypeOfDrugOrderToDrugOrderIfNotSetAndConceptNotMapped to OrderServiceTest

TRUNK-4389: Added code to set order type of drug order to drug order if not set and concept not mapped in saveOrder() method

TRUNK-4389: Added unit test and code for setting order type of test order to test order if not set and concept not mapped in saveOrder() method