Added any Data attributes from tab to Accordion

So if you have the following code:

```html
    <div id="demoTab">          
        <ul class="resp-tabs-list">
            <li data-type="fish">Shark</li>
            <li data-type="fish">Tuna</li>
            <li data-type="mammal">Whale</li>
        </ul> 

        <div class="resp-tabs-container">                                                        
            <div>Shark facts</div>
            <div>Tuna Facts</div>
            <div>Whale Facts</div>
        </div>
    </div>    
```

Then the `data("type")` attribute is now honored on both the accordion and the tab

```javascript
$('#demoTab').easyResponsiveTabs({
   activate: function (e) {
       console.log($(a.target).data("type"));
   }
});
```

Before the above would output `undefined` when running in accordion mode. Now it outputs the data type assigned to that tab.