Fix broken AMD module definition

As it stands using ftellipsis via amd produces the following error "Uncaught TypeError: object is not a function"

Eg
```javascript
require(['path/to/ftellipsis.min', function(Ellipsis) {
    var element = document.getElementById('my-element');
    var ellipsis = new Ellipsis(element);

    ellipsis.calc();
    ellipsis.set();
});
```