Provide facility for dynamic operations

[zznate]

I think this is the missing piece of being fully end-user customizable. Not quite sure how this would end up looking, but the OpType would be something like "CUSTOM" with a couple of additional attributes like

"impl" : "com.mypackage.MyIntravertHandler","busTopic" : "request.myintraverthandler"

[edwardcapriolo]

Being able to reload other handlers is good for hot patching.