Add Feign sample that fails to close a span

See gh-240

spring-cloud-sleuth-samples/spring-cloud-sleuth-sample-feign/src/test/java/sample/SampleFeignApplicationTests.java

@@ -0,0 +1,20 @@
+package sample;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.test.SpringApplicationConfiguration;
+import org.springframework.test.context.TestPropertySource;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.web.WebAppConfiguration;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@SpringApplicationConfiguration(classes = SampleFeignApplication.class)
+@WebAppConfiguration
+@TestPropertySource(properties="sample.zipkin.enabled=false")
+public class SampleFeignApplicationTests {
+
+	@Test
+	public void contextLoads() {
+	}
+
+}