TRUNK-3840: Refactoring code to display retired set member

https://issues.openmrs.org/browse/TRUNK-3840

Refactored concept.jsp; removed repeated code.
Add code to ConceptSet.java to factor in retired concepts while sorting
Added unit test for new behavior

Updated concept.jsp view and ConceptFormController
I think it is irrelevant to set retireReason and retireBy