Season 7's runner-up, David Archuleta, turns 21 years old today! We've watched David grow from a 16-year-old Season 7 Hollywood hopeful to an international star. Last week, during a concert in his hometown, David announced that he has "chosen to serve a full time mission." Watch the emotional moment in front of a live audience where talks about following his heart. David just wrapped his My Kind of Christmas Tour, his last tour in a while, although he said "I'm not finished yet. I still have som...