NASHVILLE, Tenn. – while major acts and headliners like Radiohead, Red Hot Chili Peppers, the Beach Boys and Phish always draw the masses out to the Bonnaroo Music & Arts Festival, it’s discovering new acts that’s the true joy of the four-day festival down on the farm in Manchester, Tenn. British singer-songwriter Michael Kiwanuka is one of Bonnaroo’s more buzzed-about down-list acts, but he isn’t the only rising performer worth fighting the crowds, heat and dust...