Fix API methods only called for the first item.

Example...

```html
<a href="#">Item #1</a>
<a href="#">Item #2</a>
```

```javascript
 $('a').pluginName('doSomethig');
```

...only invoked doSomething on the first anchor.
Fix extending Namespace prototype not working on IE8.

It seems IE8 is not to keen on extending prototypes in
some circumstances.
Merge pull request #3 from andrefgneves/master

Fix API methods only called for the first item.