Madonna made a surprise appearance for the ages at The Abbey in West Hollywood ... and Addison Rae helped hype up the crowd. Madge performed for about 30 minutes early Sunday morning and the packed house went crazy when she appeared in the DJ booth ... with Addison cheering her on from behind a black cat eye mask. Madonna played a mix of new and classic tunes ... including her new single, "I Feel So Free," from her upcoming "Confessions on a Dance Floor: Part II" album. In a throwback, Madonna