Everyone complains that Boston doesn’t have its own homegrown music festival — this year’s Mayfair might just be the answer. The Harvard Square Business Association this morning announced Mayfair’s May 3 music lineup lineup, and it’s a doozy: The Sheila Divine, Freezepop, Bent Shapes, M’Bolo, Air Traffic Controller, Hallelujah The Hills, Grey Season, the Luxury, Vundabar, Funeral Advantage, Parks, and the Novel Ideas all shape up a pretty killer event. And it’s free.