The year is 2004. Myspace has more than one million users, and “Yeah!,” by Usher, is blasting on repeat on the radio. The Frost Bank Tower was just completed, making it the tallest building in Austin. You might not have a cellphone, and if you do, it takes the blurriest pictures you’ve ever seen. Life is good—so good, in fact, that you might even throw a tank top on over your bathing suit and head down to Zilker Park to catch Sheryl Crow at the third-ever Austin City Limits Music Festival. Don’t forget your chunky sunglasses! It’s hard to believe that in the olden days of yore, festival outfits were rarely a priority for concert attendees. (With the number of “festival fashion” press releases we journalists…