Implement Event Channels

[dechristopher]

Setting up event listeners on predefined named channels is a feature many other datastore drivers have implemented. It's a staple of modern concurrent programming.

For example:

harper.on('error', handler(errorString){
doStuff(errorString);
});

[dechristopher]

11 Implements this partially, we still need to come up with a way to pass data through an event emission to the handlers for users to get information about the events when they fire.