WASHINGTON (Reuters) - A decision by Federal Reserve Governor Edward Gramlich to step down from his post in August underscores the rare degree to which President Bush will have a hand in molding the U.S. central bank. Bush has already named five of the seven members of the Fed's Washington-based board, although one of them, Vice Chairman Roger Ferguson, was initially chosen by President Bill Clinton. Only two members do not owe their seat to Bush: Gramlich, who said on Wednesday he will step down Aug. 31, well ahead of the expiration of his term in 2008, and Chairman Alan...