fix changing buttonText with js
fix changing buttonText with js

using $(":file").filestyle('buttonText', 'Loading...'); to set buttonText was inserting the provided text in the span used for the glyphicon
JoseVte/bootstrap-filestyle,gnachao/bootstrap-filestyle,gnachao/bootstrap-filestyle,thiagocarlossilverio/bootstrap-filestyle,JoseVte/bootstrap-filestyle,ar-icom/bootstrap-filestyle,becompany/bootstrap-filestyle,becompany/bootstrap-filestyle,r11runner/bootstrap-filestyle,ar-icom/bootstrap-filestyle,markusslima/bootstrap-filestyle,markusslima/bootstrap-filestyle,thiagocarlossilverio/bootstrap-filestyle,r11runner/bootstrap-filestyle,acemaster/bootstrap-filestyle,acemaster/bootstrap-filestyle