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-server/pom.xml

@@ -123,5 +123,20 @@
 		<start-class>org.springframework.cloud.config.server.ConfigServerApplication
 		</start-class>
 	</properties>
-
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-jar-plugin</artifactId>
+				<version>3.1.2</version>
+				<executions>
+					<execution>
+						<goals>
+							<goal>test-jar</goal>
+						</goals>
+					</execution>
+				</executions>
+			</plugin>
+		</plugins>
+	</build>
 </project>