Reduce object target area

It would be great if the object target are could be made smaller. This would be possible by adding a class to selectors.

So the code that someone would use would be
```html
<object class="fit-vids-object" width="400" height="400" data="http://www.w3schools.com/tags/helloworld.swf"></object>
```

The reason for this commit is that I am working on a post on responsive video solutions. I had add FitVids and was testing mediaelementjs.com. I was able to set it up to be responsive but in IE8 then the video wasn't displaying properly. After looking at the code I saw that FitVids was adding code to the object and that was not needed as mediaelementjs was making the object responsive.

If you make this change that then can allow for a YouTube and own hosted video using mediaelement to work together.

The user can add another selector or even increase the target are easily. It is not that easy to reduce the target area.