Fix large-uncetered to set correctly float position

See the code bellow:

```html
<div class="row">
        <div class="login-box panel small-centered small-10 large-5 large-uncentered push-7 columns">
        </div>

        <div class="hide-for-small large-7 pull-5 columns">
        </div>
    </div>
````

in this example the columns are not aligned in large screen because the large-uncentered not correct the float, which is removed by small-centered.

I put the large-uncentered to force the float: left and large-uncentered.opposite to float: right.

And it solve the problem.