As you may know, Amazon is looking for another city in which to build a vast new headquarters that could mean billions in investment and up to 50,000 jobs. Not surprisingly, just about every city wants that. But the place where it might make the most difference for the local economy is, of course, Detroit. Dan Gilbert, the Quicken Loans czar who many regard as Detroit’s capitalist savior, is heading a task force that will submit a bid in the next two days to the giant mail order retailer. Mayor