The Federal Reserve gave the improving U.S. economy a vote of confidence this past week, saying it no longer needs as much stimulus to keep growing.  The Fed's actions will raise key U.S. interest rates, but some economists say it has caused a drop in stock and currency values in some emerging markets.   The U.S. central bank has cut back economic stimulus efforts, which will push some U.S. interest rates higher. The change prompted investors to move money from emerging...