#6 - Prepare feature branch.
#6 - Upgrade integration module to Spring Integration 4.0.

In Spring Framework 4.0 and Spring Integration 4.0 a number of messaging-related types have moved from Spring Integration into Spring Framework. This commit updates Spring Plugin to depend on Spring Framework 4.0 and Spring Integration 4.0 and to use the message types that are now in Spring Framework's new spring-messaging module.