Diehard supporters of Sen. Bernard Sanders stormed media tents and staged a sit-in Tuesday night minutes after Hillary Clinton officially claimed the party’s presidential nomination, injecting another round of drama into the convention and pouring cold water on claims Democrats are fully uniting behind their White House nominee. Hundreds of Sanders backers, most carrying signs backing their candidate, conducted what seemed to be a well-coordinated march from the Wells Fargo Center to the media tents just outside the arena. They said that party officials were trying to confiscate Sanders signs inside Wells Fargo