BOUREIMA BALIMA and DAVID LEWIS SIX gunmen on motorbikes with AK-47 assault rifles kidnapped an American man from his home on the edge of a rural village in southern Niger in the early hours of Tuesday, multiple sources said. The kidnappers seized 27-year-old Philip Walton, who kept camels, sheep and poultry and grew mango trees near the border with Nigeria, at around 0145 local time (0045 GMT), a police source, two local officials and three security sources told Reuters. His wife, young daughter and his brother were left behind in their home in the village of Massalata, the police source…