WASHINGTON (MarketWatch) - The Commodity Futures Trading Commission said Tuesday it has filed civil lawsuits against 15 natural gas traders for reporting false information on deals to industry newsletters in an attempt to manipulate market prices.The traders worked for Enserco Energy, Mirant Americas Energy Marketing (MIRKQ: news, chart, profile) , Cinergy Corp. (CIN: news, chart, profile) , Duke Energy Trading and Marketing (DUK: news, chart, profile) , CMS Field Services (CMS: news, chart, profile) , and Shell (RD: news, chart, profile) affiliate Coral Energy Resources, when they carried out these activities, the commission said in a statement. Concord Energy, a...