Implementation opt-in error handling #8?

Hey, 

we have implemented a model plugin to handle errors. It's necessary for this, to get request errors (e.g. timeout/crossdomain) and return them on the "end" of a request.
Furthermore it's possible with this modification to manipulate the error info/data that is passed to the model callbacks (e.g. save( function(err){} )).

Perhaps this was something you meant with this issue (https://github.com/component/model/issues/8) also?
I'm excited about your feedback!

Frank.