Rebecca Rubin Film and Media ReporterRachel McAdams and Abby Ryder Fortson have been cast in “Are You There God? It’s Me, Margaret,” an adaptation of Judy Blume’s beloved coming-of-age book.Ryder Fortson will play Margaret Simon, a sixth grade girl who is going through puberty and searches the universe for any answers she can find. McAdams is portraying Margaret’s mother, Barbara.