Ever since his single “War Sweater” jettisoned him into stardom five years ago (thanks to a game-changing plug on One Tree Hill), the indie-pop singer has built a following that’s as passionate as his compositions. His fans have bought 45,000 copies of his self-released debut, the exquisitely tortured Almost Everything I Wish I’d Said the Last Time I Saw You. Salvation’s first single, the bright, palpitating “Wake Up (Lily I Love You),” is already off to an auspicious start, amassing global grassroots traction.