Fix packaging for Layout.NONE

Fixes gh-139

spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/Repackager.java

@@ -145,7 +145,9 @@ public class Repackager {
 					}
 				}
 			});
-			writer.writeLoaderClasses();
+			if (!(this.layout instanceof Layouts.None)) {
+				writer.writeLoaderClasses();
+			}
 		}
 		finally {
 			try {

spring-boot-tools/spring-boot-loader-tools/src/test/java/org/springframework/boot/loader/tools/RepackagerTests.java

@@ -148,6 +148,7 @@ public class RepackagerTests {
 		Manifest actualManifest = getManifest(file);
 		assertThat(actualManifest.getMainAttributes().getValue("Main-Class"),
 				equalTo("a.b.C"));
+		assertThat(hasLauncherClasses(file), equalTo(false));
 	}
 
 	@Test
@@ -160,6 +161,7 @@ public class RepackagerTests {
 		Manifest actualManifest = getManifest(file);
 		assertThat(actualManifest.getMainAttributes().getValue("Main-Class"),
 				equalTo(null));
+		assertThat(hasLauncherClasses(file), equalTo(false));
 	}
 
 	@Test