(Reuters) – The Rolling Stones will play Britain's Glastonbury music festival for the first time, organizers announced on Wednesday, joining Arctic Monkeys and folk band Mumford & Sons as headliners at the three-day June event. The appearance by the veteran British rock group follows weeks of rumors that the Stones, who in 2012 celebrated 50 years in the music business with a handful of concerts, finally would play at Glastonbury, one of Europe's biggest music festivals. …