Make sure ThymeleafAutoConfiguration works if imported directly

Before this change if Layout dialect not available then the nested class is
loaded and barfs because it depended on the layout dialect (in a
@ConditionalOnClass annotation).

spring-bootstrap-cli/samples/ui.groovy

@@ -0,0 +1,11 @@
+@Grab("org.thymeleaf:thymeleaf-spring3:2.0.16")
+@Controller
+class Example {
+
+	@RequestMapping("/")
+	public String helloWorld(Map<String,Object> model) {
+		model.putAll([title: "My Page", date: new Date(), message: "Hello World"])
+		return "home";
+	}
+
+}