More than 100 people gathered just before noon Saturday outside the Honey Bowen Building, marched about a mile along South Main Street and held a rally outside the Bulloch County Courthouse.Their cause: “Justice for Trayvon.” The organizers -- a group of Georgia Southern University students calling themselves “The Caucus,” -- set up the march and rally to support a nationwide push for more than 100 similar rallies. It was in response to the 2012 fatal shooting of 17-year-old Trayvon Martin by George Zimmerman, a Neighborhood Watch volunteer in a Sanford, Fla., neighborhood and Zimmerman’s subsequent acquittal by a Florida jury.