INT-3007 Add WARN Log When Advice Skipped

Previously, when a MessageHandlerAdvice is applied to something
other than a MessageHandler, the advice was silently skipped.

Add a WARN log message that warns that the advice is not applied.

Add a test case that ensure the log is emitted when the
advice is applied to a Poller.
Merge pull request #801 from garyrussell/INT-3007

* INT-3007: Add WARN Log When Advice Skipped