'USS Constitution' honors both Boston First Responders and the Battle of Midway with a 21-gun salute in Boston Harbor. During the ship's first underway this year a special tribute was paid to first responders to the events surrounding the April 15 Boston Marathon bombings and to commemorate the 71st anniversary of the Battle of Midway, June 4. More than 375 guests accompanied the 215-year-old Constitution on the commemorative underway, including first responders from the FBI, City of Boston Fire…