User answer compaction should only be available to admin users and only on an exam wide basis.

We need to update tests so that they can handle the new format of answer submission from rts (although this may actually be due to a bug in the underlying submission code):             

res = client.post(reverse("global_exam_answers_submit"), data=post_json)
            json_res = json.loads(res.content)
            assert json_res["success"] == False
>           assert json_res["error"] == "Invalid data"
E           AssertionError: assert 'user / cid mismatch' == 'Invalid data'
E             
E             - Invalid data
E             + user / cid mismatch