Billionaire Ken Griffin said his hedge fund’s  Chicago footprint will shrink to just two floors as crime, taxes and other challenges push employees to relocate to Miami and New York. “Chicago, you know, over the last, unfortunately, over the last six or seven years, has been engulfed in a series of problems,” Griffin said at the Citadel Securities Future of Global Markets conference in New York on Oct. 6.  The Windy City, which served as Citadel’s headquarters for more than 30 years, has seen