Friday won’t see a single data release, but there’s plenty on the minds of investors as worries abound that the U.S. currency could lose its AAA-rating . In addition, two gloomy speeches from central bank officials Thursday evening brought the U.S. dollar down a notch overnight. Federal Reserve chairman Ben Bernanke speaks to graduates of Boston College Law School at 2pm, but there’s no Q&A. Judging by his graduation speech to Harvard last year, there’s little potential...