Explore making protocol handlers more modular

[bmenrigh]

Right now the HTTP (and to a lesser extend SMTP) protocol handling is just built straight into the code and isn't modular at all. It would be nice if all the stuff needed to handle a protocol were put together into a file with a clearly defined API to implement reading and interacting and logging of the activity.

The main benefit of this would be at a code organization level. It might also lower the bar to adding support for more interactive protocols or extending the interactivity of an existing protocol like SMTP.