Bob Dylan is a lot of things, but ‘upbeat’ isn’t a word that could often describe the veteran songwriter. Despite the countless different genres and styles he has explored since his days as a young folk singer, there are a few specific sounds that inspire little but boredom in Dylan’s mind, and heartland rock is at the top of that list. First emerging during the latter days of the 1970s, heartland rock isn’t so much a sound as it is a spirit; de…