Experimental: Support Gradle --parallel

This should be treated as experimental but with these changes it seems to build ok.

BUILD SUCCESSFUL

Total time: 5 mins 15.533 secs

It turns out that our sporadic Redis problems were fixed in a later version of Jedis.

The problem was that the `connection.subscribe()` exited immediately. When I started adding debug
logic, the problem went away (because I was using a newer versio of Jedis).

spring-data-redis 1.5.2 is updated to work with the 2.7.3 version of Jedis.

Polishing

spring-integration-websocket/src/test/java/org/springframework/integration/websocket/ClientWebSocketContainerTests.java

@@ -66,6 +66,7 @@ public class ClientWebSocketContainerTests {
 
 		TestWebSocketListener messageListener = new TestWebSocketListener();
 		container.setMessageListener(messageListener);
+		container.setConnectionTimeout(30);
 
 		container.start();