Replacing js file with original js v.1.0.3 to fix issue on default input not hidden.

Hi, I started using the gem and I noticed that when you call ```$(":file").filestyle();``` the default input file is still appearing on the page. I checked the js code and saw that this section (~lines 164) from the original js file is missing in your vendor/assets/javascripts/bootstrap-filestyle.js 

The problem was that in your version the element is position -500 pixels to the left, which makes that the default file input remains visible.