Wrapping LoadBalancerFeignClient in tracing representation

without this change when using SC-Netflix 1.2.0 Feign can't call an external URL

fixes #393

spring-cloud-sleuth-core/pom.xml

@@ -141,6 +141,11 @@
 			<artifactId>h2</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-starter-eureka</artifactId>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 
 </project>