By Cris Chinaka HARARE (Reuters) - South Africa's President Jacob Zuma on Sunday congratulated Zimbabwean leader Robert Mugabe on his re-election, in sharp contrast to Western governments which questioned the credibility of a rushed, disputed vote. African monitors broadly approved the conduct of the election but Mugabe's main rival, Movement for Democratic Change (MDC) leader Morgan Tsvangirai, has said he will challenge the results in court with evidence of massive vote-rigging, irregularities and intimidation. ...