Added quorum_lookup

quorum_lookup picks lookup_result_enties by following rules:
1. If there are quorum lookup_result_enties with the same
timestamp, they are the final result
2. Otherwise the final result is lookup_result_enties with
the greatest timestamp
Please, use ELLIPTICS_REQUIRE_ERROR for this cases, you may see example of it's usage at test_lookup_non_existing.