by Luana Sarmini-Buonaccorsi and Stuart Williams in Istanbul © Agence France-Presse ANKARA, Turkey (AFP) — President Recep Tayyip Erdogan on Sunday faces the biggest ballot box challenge of his 15-year grip on Turkey, seeking to overcome a revitalized opposition against the background of an increasingly troubled economy. A self-styled heavyweight champion of campaigning, Erdogan has won successive elections since his Islamic-rooted ruling party came to power in 2002, transforming Turkey with growth-orientated economic policies, religious conservatism […]