WASHINGTON, June 7 -- The U.S. Department of Justice issued the following news release: The former president of a Texas energy company was sentenced today to six years and six months in prison for his role in an illegal kickback scheme and a commodities insider trading scheme involving natural gas futures contracts. According to court documents, Matthew Clark, 56, of Needville, Texas, conspired with others to direct his employer's trades to Houston-based Classic Energy LLC, a brokerage firm ow  more