MULE-8018: Merge http connector code cleanup

Let's try to approach this differently:  I agree with you 100%, but only if you change the following to recieve a DefaultHttpListenerConfig and also remove the downcast.  https://github.com/mulesoft/mule/pull/1163/files#diff-0c94f6ef7ce2a6f96208cb4e963ca24dR230