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 
:+1: 
However I'm not fine with `Abstract*` prefix noise, because the class is `abstract` by nature independently of the name. 
We can discuss on the matter off-line or just follow with existing rule. Is there one ?