Nate Vecchiarelli

Add support for different sized btn's

1

Add support for different sized buttons or bring back the data-styles attribute to allow passing classes to the button element such as [btn-sm](http://getbootstrap.com/css/#buttons-sizes) Place for [fix](https://github.com/lordfriend/nya-bootstrap-select/blob/master/src/nya-bs-select.js#L67)