John Darnielle, singer and songwriter for the Mountain Goats, pours energy into a song at his M-Shop concert Saturday night. People came from as far away as Philadelphia and St. Louis to hear the Ames one-man-band perform. The Mountain Goats have built a cult following around the world, and Darnielle’s new record, “The Coroner’s Gambit” is doing well on college radio. A packed M-Shop crowd sat on the ground staring up at Darnielle as he strummed his guitar and sang songs that span his 10-year career. Darnielle ended the performance with a fun cover version of Ace of Base’s “The Sign.”