Revamped eMusic.com Targets Indie Market By ALEX VEIGA    LOS ANGELES (AP) -- Nearly a year since it was sold by Vivendi Universal (V) to private investors, online retailer eMusic has undergone a facelift that includes a panel of music critics to help users comb its trove of independent music.    The revamped service, scheduled to debut Wednesday, is the latest evolution for the pioneering retailer, the first to sell digital music files online in the late 1990s...