(Reuters) - London's FTSE 100 rebounded on Thursday, led by strong gains in oil majors and miners as investors were encouraged by signals the U.S. Federal Reserve is preparing to cut interest rates soon, while electronics retailer Dixons Carphone tanked. The FTSE 100 index was up 0.4% and the FTSE midcap index rose 0.5% by 0736 GMT with BP and Shell both up more than 1% after Middle East tensions drove crude prices higher. The U.S. Federal Reserve kept interest rates unchanged on Wednesday and..