Move over, Ashton Kutcher — President Barack Obama is the new "master Tweeter." In an exchange at the end of this week's White House West Wing Week video, Obama jokingly refers to himself as the "twoosh master" after crafting a perfect 140-character tweet. Obama became the first sitting president to hold a Twitter question and answer session Thursday after a campaign event in Des Moines, Iowa. During the session, he responded to a question from @jwarner180 on alternative energy sources using each of Twitter's 140 allowed characters, which he's told in the video is called a "twoosh," or "Twitter swoosh."...