Implement a pipeline in other runners

Original LP Author: Barry Warsaw , LP Link: https://bugs.launchpad.net/bugs/975702

Stephen observed that it might be useful to implement a pipeline of handlers (even chain processing?) for other runners such as archive, bounce, and command. This is probably not something for 3.0 final, thus I'm marking it triaged,low. But it's an interesting idea and may lead to other useful refactoring.