Years before he slaughtered 49 people at a gay club, Orlando shooter Omar Mateen was threatening to go on a school rampage, according to a former classmate. In fifth grade, the future gunman said that he was going to bring a gun to school and kill the students, fellow Mariposa Elementary alumnus Leslie Hall told TMZ. Hall, who said that she was bullied by Mateen at the Port St. Lucie, Fla., school, told the outlet that he was suspended for two weeks because of the threat. The 29-year-old’s threat would have likely come in the late 1990s, during a series...