fixed integration tests that were failing

- discovery_search
    * added MAX_SEARCH_RESULTS parameter, can be set in config or defaults to 250. This should be viewed as a network dependent parameter (how many results should be returned if user does not specify)
    * reintroduced the tier-1 concept (no and/or). This branch returns an elastic search object (so resour
ce is available at ['_source'] in response (see test_basic_searching in ion/services/dm/presentation/test/discovery_test.py for example)

- discovery_test
    * several tests required id_only to be True

part of OOIION-1208