Thanks to an early push from the music blogs, Eau Claire native Justin Vernon has found unexpected success with his singer-songwriter project, Bon Iver, whose debut album, For Emma, Forever Agohas been heralded as one of the year’s best. Bon Iver returns to Milwaukee tonight for an 8 p.m. concert at the Pabst Theater that promises to include some of Vernon’s harder, edgier songs, as well as the harrowing, acoustic folk for which he’s best known.