LONDON, Dec. 17 (Reuters) – Amazon.com Inc. was marketing a collection of speeches and writings by President Xi Jinping on its Chinese website about two years ago when Beijing issued an edict, according to two people familiar with the incident. The American e-commerce giant no longer has to allow customer ratings and reviews in China. A negative review of Xi’s book sparked demand, said one of the people. “I think the problem was all below five stars,” said the other person, the highest rating on Amazon’s five-point system. Ratings and reviews are an integral part of Amazon’s ecommerce business and...