locking mechanism for encounter_type - TRUNK-4033

[TRUNK-4033] made some changes

added a testcase, and made some other changes

[TRUNK-4033] added a disabled attribute if encounterTypesLocked == 'true'

[TRUNK-4033] added a testcase i.e. EncounterService.saveEncounterType_shouldNotSaveEncounterTypeIfEncounterTypesAreLocked()

[TRUNK-4033] added some other testcases and made some changes

Removed or converted throws clauses for EncounterTypeLockedException to APIException - TRUNK-4033

Conflicts:
	api/src/main/java/org/openmrs/api/EncounterService.java
	api/src/main/java/org/openmrs/api/impl/EncounterServiceImpl.java
	api/src/test/java/org/openmrs/api/EncounterServiceTest.java
	webapp/src/main/webapp/WEB-INF/messages.properties