FOREX-Dollar gains slightly after U.S. jobs data stokes optimism

* Traders eye nonfarm payrolls growth (Updates prices, adds comments; NEW YORK, July 31 (Reuters) - The U.S. dollar edged higher against a basket of major currencies on Thursday after U.S. labor market data bolstered expectations for a more hawkish Federal Reserve and reinforced optimism for a strong U.S. nonfarm payrolls report Friday. The Labor Department said the Employment Cost Index, the ...