Rage Against the Machine frontman Zack de la Rocha is stepping up his campaign to compel the state of Arizona to repeal its controversial immigration law. In addition to adding Ry Cooder, Nine Inch Nails, and comedian Chris Rock to the growing list of artists who are refusing to perform there as part of The Sound Strike boycott effort, de la Rocha tells Billboard.com that plans are in the works for a series of protest concerts in July. "In the coming weeks we are going to be organizing a series of concerts that are respectful of the nature of the...