Missing z-index on .zoomContainer and .zoomWindowContainer

I recently experienced a problem when using elevateZoom (3.0.0) in latest Chrome (28.0.1500.95) on a website using z-index on several elements (container, header etc.)

The missing z-index on zoomContainer and zoomWindowContainer hid the zoomLens and tint. Basic configuration didn't show up anything.

Here is the JavaScript I used:

```javascript
var $sourceImg = $('.source img'),
    $sourceContainer = $('.source');
$sourceImg.elevateZoom({
    borderSize: 0,
    easing: true,
    responsive: true,
    zoomWindowHeight: $sourceContainer.height(),
    zoomWindowPosition: 'zoom',
    zoomWindowWidth: $sourceContainer.width()
});
```
While using this Markup and CSS:

```html
<body>
    <div class="container">
        <div class="source">
            <img src="image1large.jpg" alt="" data-zoom-image="image1large.jpg">
            <div class="caption">Abbildung Lorem Ipsum</div>
        </div>
        <div id="zoom" class="zoom"></div>
    </div>
</body>
```
```css
.container {
    z-index: 30;
}
```
When setting a high z-index on zoomContainer and zoomWindowContainer like the zoomLens has (999) it works as expected.

![elevatezoom-zindex-bug](https://f.cloud.github.com/assets/1336590/885807/3708f584-f9db-11e2-8e03-58e37264321e.jpg)