LAGOS (Reuters) – Nigeria’s opposition People’s Democratic Party (PDP) said on Monday it will choose a presidential candidate at the end of May to contest elections set for February next year as it seeks to return to power after losing office seven years ago. Veteran politician and former vice president Atiku Abubakar is seen as front-runner to represent the opposition. It will be his sixth attempt at the presidency if he contests the election. The PDP ruled Africa’s most populous nation at the advent of multi-party democracy in 1999 but was swept from power in 2015 by President Muhammadu Buha…