African nations will officially launch a landmark trade agreement at an African Union summit in Niger on Sunday, with the long sought-after agreement hailed as a historic step towards peace and prosperity across the continent. The deal, which African leaders hope will create the world's largest free trade area, was given a boost when Nigeria and Benin's presidents signed on to rapturous applause on Sunday at the two-day summit in Niger's capital Niamey. After 17 years of tough negotiatio ......