DC VILLAINS Rock trio, comic-book characters, video-game entrepreneurs or TV stars? These guys want it all     If their name conjures up images of scheming politicians or comic-book ne’er-do-wells, the members of the Nashville-based rock band DC Villains don’t mind at all. “Bad guys are often cooler than the good guys,” says frontman Damon Carroll (the first part of the moniker is derived from his initials). “And sometimes the bad guys...