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 note that 'opposite time' is related to current synchronous lookup, but in this case it also means that only result until first correct object is returned, potentially not from every group/replica.

Or just drop this last sentence, it is rather vague