Polish GemFire

* Remove Compile Warnings
* Correct @since
* Add tests
* Add to What's New in documentation

samples/httpsession-gemfire-clientserver/src/main/java/sample/ServerConfig.java

@@ -81,6 +81,7 @@ public class ServerConfig {
 		return cacheServerFactory;
 	}
 
+	@SuppressWarnings("resource")
 	public static void main(final String[] args) throws IOException { // <5>
 		new AnnotationConfigApplicationContext(ServerConfig.class)
 			.registerShutdownHook();