Using the options.type doesn't work

In the readme, it mentions that I can set the type of the notifications in the options using the type property

``` JavaScript
{ title: "Session Expired!", message: "Please login in again.", type: "warning" };
```

But this will always show up as a primary notification. Is this the expected behavior? After some debugging, I was unsure if this [line](https://github.com/alexcrack/angular-ui-notification/blob/e617de2eb11b43f3cf388aea3ae32668c94cf097/src/angular-ui-notification.js#L47) should be change to

``` Javascript
args.type = t || args.type || '';
```