Mayor Bloomberg's popularity rating has dropped to its lowest level in five years, in part because of his ardent defense of a proposed mosque several blocks from Ground Zero, according to a poll released yesterday. New Yorkers' approval of their third-term mayor (pictured) dipped to 49 percent, down from 56 percent in April, as 53 percent of those surveyed said they disagree with his position on the mosque, according to the Marist survey. "The mosque is not doing him any good . . . He's certainly on the wrong side of public opinion on that in the city," said pollster...