Kate Nash is tired. It's 9 p.m. and she's on her first major U.S. tour, knitting a scarf in her hotel room in Atlanta and occasionally yawning. And for good reason — it's been a busy couple of years. The 20 year-old English singer-songwriter wrote her first song and played her first live gig two years ago, then went from a spot in Lily Allen's Myspace Top 8 to the top of the English charts......