CAMBRIDGE, Massachusetts — Harvard University says it's partnering with business titan Michael Bloomberg to provide leadership training to mayors across the U.S.Bloomberg, a former New York City mayor, is donating $32 million to start the Bloomberg Harvard City Leadership Initiative, which aims to train up to 300 mayors over the next four years.Mayors invited to the program will gather in New York City for three days to learn from Harvard faculty and then continue the year-long program online.