Adds support for property origin tracking in config server/client

Adds a new format if requested using v2 Accept header, otherwise the
format is backwards compatible so older clients will work with new
servers.

fixes gh-866

spring-cloud-config-sample/pom.xml

@@ -35,6 +35,13 @@
 			<artifactId>spring-cloud-config-server</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-config-server</artifactId>
+			<type>test-jar</type>
+			<scope>test</scope>
+			<version>${project.version}</version>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>