By Jonathan Allen NEW YORK (Reuters) - Chinese dissident Chen Guangcheng called on the United States on Friday to ensure his family in China would be treated fairly, saying his imprisoned nephew was not receiving proper medical care from Chinese authorities, whom he accused of "hooligan tactics." Chen, who made international headlines last year when he escaped house arrest and spent 20 hours on the run before finding refuge at the U.S. Embassy in Beijing, said his nephew was suffering from appendicitis and being treated only by a fellow inmate who had received some medical training. ...