clean up Reply* methods to make way for pref-based routing
clean up Reply* methods to make way for pref-based routing

I've been putting this off but it's an important feature, so for
now I've organized the code for it to happen and added notes about
what I need to do to implement it. Most of the basics exist in the
Slack broker for the image table replies and that needs to be lifted
over and cleaned up.

Netflix/hal-9001