Singer and songwriter John Mellencamp will receive an award named for Oklahoma native Woody Guthrie.      The Woody Guthrie Center in Tulsa, Oklahoma, announced that Mellencamp will be presented with the Woody Guthrie Prize during an August 30 ceremony.      The annual prize is given to an artist who best exemplifies the spirit and life work of Woody Guthrie by speaking for the less fortunate and serving as a positive force for social ch…