Delete Appointment By Id

Added method to controller, test, exception classes etc.
Merge remote-tracking branch 'origin/feature/InterviewScheduler/deleteAppointmentById' into develop_candidate_1

Conflicts:
	interview-sheduller/src/main/java/com/softserveinc/ita/controller/AppointmentController.java
	interview-sheduller/src/main/java/com/softserveinc/ita/service/AppointmentService.java
	interview-sheduller/src/main/java/com/softserveinc/ita/service/AppointmentServiceMock.java
	interview-sheduller/src/main/resources/mvc-dispatcher-servlet.xml
	interview-sheduller/src/main/webapp/WEB-INF/mvc-dispatcher-servlet.xml
	interview-sheduller/src/test/java/com/softserveinc/ita/mvc/AppointmentTests.java