By Emma Farge GENEVA (Reuters) – Switzerland will try a former Gambian minister under ousted dictator Yahya Jammeh for crimes against humanity on Monday in a milestone case where a serial rape victim will testify after a multi-decade wait for justice. Former interior minister Ousman Sonko will become the highest-ranking official to be tried in Europe under the principle of universal jurisdiction that allows grave crimes to be prosecuted anywhere, said Swiss campaign group TRIAL International which filed the complaint against him. Nine Gambian plaintiffs will travel to Switzerland for the sched…