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
Double alreay implements compareTo, so you don't need to manually do it here, OpenmrsUtil should work