Restore setDefaultChannel to MessagingTemplate

Synonym for the Spring setDefaultDestination for backward compatibility.
Merge remote-tracking branch 'upstream/master' into 4.0.0-WIP

Conflicts:
	build.gradle
	spring-integration-amqp/src/main/java/org/springframework/integration/amqp/channel/AbstractSubscribableAmqpChannel.java
	spring-integration-core/src/main/java/org/springframework/integration/channel/ExecutorChannel.java
	spring-integration-event/src/main/java/org/springframework/integration/event/inbound/ApplicationEventListeningMessageProducer.java
	spring-integration-file/src/test/java/org/springframework/integration/file/recursive/FileInboundChannelAdapterWithRecursiveDirectoryTests.java
	spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/TcpConnectionEventListeningMessageProducer.java
	spring-integration-jdbc/src/test/java/org/springframework/integration/jdbc/StoredProcOutboundGatewayWithNamespaceIntegrationTests.java
	spring-integration-jdbc/src/test/java/org/springframework/integration/jdbc/config/JdbcOutboundGatewayParserTests.java
	spring-integration-jdbc/src/test/java/org/springframework/integration/jdbc/config/StoredProcInvalidConfigsTests.java
	spring-integration-jms/src/main/java/org/springframework/integration/jms/SubscribableJmsChannel.java
	spring-integration-jpa/src/test/java/org/springframework/integration/jpa/outbound/JpaOutboundGatewayIntegrationTests.java
	spring-integration-redis/src/main/java/org/springframework/integration/redis/channel/SubscribableRedisChannel.java
	spring-integration-security/src/test/java/org/springframework/integration/security/SecurityTestUtils.java
	spring-integration-xml/src/main/java/org/springframework/integration/xml/selector/XmlValidatingMessageSelector.java

Resolved.
Fixes For Final Spring 4 Polishing

- MessageConverter moved
- MessagingException.failedMessage is immutable
- Cast needed on messagingTemplate.receive()