For decades, George Howell has been at the forefront of a revolution to transform coffee from a commodity into a craft. Today, his influence stretches from his small roastery on School Street in Acton to coffee farms around the world. Howell’s search for the best beans has taken him to high altitude coffee farms in Yemen, the birthplace of coffee cultivation, to Guatemala, Kenya, Costa Rica, and beyond. Howell discovered high quality specialty coffees when he moved to the San Francisco Bay area after graduating from Yale University in 1968. Like fine wines, coffee can have unique flavors, such as…