(Editor's Note: This story has been updated to include comments from GPS III prime contractor Lockheed Martin and navigation payload provider Exelis.) Ongoing delays with the navigation payload for the Air Force's next-generation Global Positioning System satellite will delay the delivery of the satellite and could push the launch date past the current 2015 target. The GPS III navigation payload, which is being built by Exelis, was to be delivered last August but was delayed until early this year...