Shanna Moakler taking aim at Kourtney Kardashian? On August 11, the reality star showed support for her husband Travis Barker by attending the premiere of his new documentary, Travis Barker: Louder Than Fear, at the Academy Museum in Los Angeles. The couple walked the red carpet along with his three children, Atiana De La Hoya, Alabama Barker, and Landon Barker, whom he shares with ex-wife Shanna. A clip of the family posing together at the even…