PARIS (Reuters) - Kering's shares fell by nearly 6 percent on Thursday after signs of a slowdown at the French fashion company's Gucci brand, particularly in the United States, took the shine off a broader rise in sales.Traders and analysts honed in on Gucci as one of the main reasons for the drop, along with profit-taking, after Kering said on Wednesday that first quarter revenues had risen 21.9 percent to 3.8 billion euros (£3.3 billion)."There were two dark spots ... Gucci U.S. decelerated..