need "tagged" event

[jamienk]

In order to have my user's changes auto-saved, I need to have some sort of "tagged" event that fires whenever a tag is added, edited, or removed. I've clumsily added

$(this).trigger('tagged');

into the few choice spots in the code, but it's clearly not ideal so I don't want to do a pull request. I read this #11 but I'm not sure how to implement it the way it is recommended there.