TRENTON, N.J., May 21 -- Mercer County issued the following news release: Summer may not officially be here, but the recent pleasant weather has everyone heading outdoors for fun and sun. Mercer County's annual Freedom Festival, Music in the Park series and second annual Burger Mania are family-friendly events that offer great times at bargain prices. Each concert features vendors, play areas for children and an adult beverage area. Freedom Festival, which Mercer County co-sponsors with WP  more