LOS ANGELES (Reuters) – Concertgoers won't have to leave their homes to enjoy the "Live Music Day Festival," the biggest online-only event of its kind, music networks MTV, VH1 and CMT said on Tuesday. The 24-hour virtual concert is set to kick off at 7 p.m. EDT on June 19 and will feature performances by more than 50 bands and artists spanning rock, indie, pop, R&B and folk. Acts include Hanson, Atlas Genius, Labrinth, Langhorne Slim and Kate Nash. The performances, accompanied by the fan-picked O Music Awards, will be streamed live from Viacom's offices in New York, Nashville and Los Angeles. …