Bon Iver's gruff voice accusing "I can see you standing, honey, with his arms around your body" on track four of Taylor Swift's new album, Folklore, is startling.Just as the whole record came as a surprise this week, his deep, raw vocals are a welcome jolt, juxtaposed against Swift's airy "I had a marvelous time ruining everything" admission fading out from the set's previous track, "The Last Great American Dynasty."So how did Bon Iver (real name Justin Vernon) find his way onto Folklore?The