Could we maybe simplify the whole 'type'/'class' thing to just use classes?

```
$(".my-element").message({
  "message":"An error! Oh noes!",
  "class":"error"
});
```

Then they can use the built-in messages classes, or specify their own. And they don't really need to know any additional info about how it works, either way. I think this is more how the Bootstrap JS plugins work...