Adds Events part 1.

This is the first part of a 2-part post to respond to [this blog post](http://naturaily.com/blog/post/marionette-plain-object-over-reqres-commands-above-all)
what does `idempotent` mean? I'm guessing it means this?
> The first time you call it the Channel will be made for you, while subsequent calls return that same Channel.