Update Bootstrap to version 3.2. Closes #1604

New version of Bootstrap has been released. For details please see:

[http://blog.getbootstrap.com/2014/06/26/bootstrap-3-2-0-released/](http://blog.getbootstrap.com/2014/06/26/bootstrap-3-2-0-released/)

This commit updates version
used by JSBin libraries.
After the update if Bootstrap latest menu option is used following scripts will be inserted into page content:

```html
<script src="http://code.jquery.com/jquery.min.js"></script>
<link href="http://maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css" rel="stylesheet" type="text/css" />
<script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js"></script>
```

tested locally with current master