Add generic framework support

Hey again, John :)

I've added a generic handler which is used if the framework isn't officially supported, but this should do the trick for most (if not all) current and future frameworks.

I wrote [Fathom.js](http://markdalgleish.com/projects/fathom/) a while ago, and I've begun dabbling with a new one called [Bespoke.js](https://github.com/markdalgleish/bespoke.js), and this update would make it work with either of these without any further modification, so I think it's a pretty big win.

Thanks :)