As I watched Ken Loach's newest film, “Jimmy’s Hall,” I was struck by how, as had also been true in “The Wind That Shakes the Barley,” Paul Laverty’s writing and Loach’s directing of that writing is free of pretension. Loach (pictured, foreground) doesn’t need fantastic sound tracks or the latest and greatest special effects to make a thoroughly enjoyable film, nor indeed does he need to put the…