LOS ANGELES (AP) Sean Penn's "The Gunman" was no match for the rebel kids of "Insurgent."The second installment in the "Divergent" series easily topped the box office with $54 million from 3,875 theaters, according Rentrak estimates Sunday. Penn's geopolitical thriller stumbled with only $5 million.While the second films in both the "Hunger Games" and the "Twilight" series boasted opening...