Muted option doesn't apply to change event

When using the picker in a form which is monitored by a change listener, trouble arises.

Imagine:

``` JavaScript
$('form').change(function(){

if ( condition_is_met ) {

// This would fire the change event again, causing an infinite loop.
picker.clear();

// Only prevents the 'set' event, and thus doesn't resolve the issue.
picker.clear({ muted: true });
}
});
```

Perhaps the `muted` option should prevent the `change` event from being fired. I'd make a pull request, but I'd expect current implementations to rely on the change event _always_ being fired on a `set` call.