THE BRONX - Con Edison and union workers have resumed negotiations today, as workers hope to end a lockout. Thousands of union employees say they want to send a message to the company's managers that they won't back down. Federal mediators were on hand today to cool any rising tempers, and hopefully get a contract signed. About 5,000 managers are currently doing the work of 8,500 union employees. Con Ed, union workers hope to continue talks Thursday