make path argument receive sources object

```html
<div data-vide-bg='{"mp4": "video/ocean.mp4", "webm": "video/ocean.webm", "ogv": "video/ocean.ogv", "poster": "video/ocean.jpg"}'></div>
```

```javascript
$("#block").vide({
    'mp4': 'video/ocean.mp4',
    'webm': 'video/ocean.webm',
    'ogv': 'video/ocean.ogv',
    'poster': 'video/ocean.jpg',
});
```