Int 3460: Support output-channel when an AbstractCorrelatingMessageHandler is 'ref'd by a Service Activator	

INT-3460: Support output-channel when an AbstractCorrelatingMessageHandler is 'ref'd by a Service Activator	

* allow AbstractCorrelatingMessageHandler's output referenced by service-activator output-channel
* add test 
`@DirtiesContext` as well. It properly closes the CTX after test-class. By default `SpringJUnit4ClassRunner` doesn't do that. It can be useful in some cases, but for us it is dangerous: we have to avoid any test classes cross talks.