TRUNK-3098: Add unit-test getConceptsByAnswer_shouldFindAnswersForConcep...

I added a unit-test for the TRUNK-3098 issue [1].  The unit-test passed and I believe the issue can be closed, based on the issue's comments.

Please let me know if anything more needs to be done or if I missed something.

[1] https://tickets.openmrs.org/browse/TRUNK-3098