Fix messaging and ribbon instrumentation for hex headers

It still feels brittle because it's up to the suthor of the
instrumentation. This patches all the places where we were still
using Long instead of Long.toHexString(..).

Fixes gh-125

spring-cloud-sleuth-samples/spring-cloud-sleuth-sample-zipkin-stream/pom.xml

@@ -28,11 +28,6 @@
 			<artifactId>spring-boot-configuration-processor</artifactId>
 			<optional>true</optional>
 		</dependency>
-		<dependency>
-			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-boot-devtools</artifactId>
-			<optional>true</optional>
-		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-jdbc</artifactId>