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 write a test case description - why test is needed, what it is intended to do, what it does and how it checks that everything is correct. It is needed to export test information to public via doxygen. Its a pity we do not yet have this for all existing tests.