MARACAIBO, Venezuela (Reuters) -Venezuela presidential hopeful Manuel Rosales said on Wednesday he was willing to hand over his place on the ballot to a unity candidate, amid uncertainty over who will carry the opposition's banner in a July contest against President Nicolas Maduro. Neither the landslide winner of an October opposition primary nor her alternate were able to register for the race before a Monday deadline, though two opposition groups, including Rosales' A New Time party, managed t