Story 1869. Updated code based on Brian's code review comments. A couple of unit tests are still not working. The mockPersistence object does not seem to throw an exception as expected.

added GroupDetailSelector so GroupPersistence implementation can configure whether group details should be returned from searches

ac2 rework: add JsonInputter to parse a json String into a DOM, updated JSON readers and writers to use the cadcUtil Json Inputter and Outputter.