BOSTON — The Boston Marathon is giving runners who use music as motivation free access to elite competitors' playlists and tips.John Hancock, which sponsors the marathon, says it's teamed up with Spotify to let participants in next month's race listen to champion runners' favorite music.Elite athletes contributing tracks to the project include four-time Olympian Shalane Flanagan, who holds the American women's record on the Boston course; 2014 winner Meb Keflezighi; and Tatyana McFadden, a Paralympics gold medalist and four-time Boston Marathon champion.