fix for IE7 and protocol agnostic urls

On IE7 only, the `<link href="//same_domain/stylesheets/site.css">` element 
will trigger a Cross-Domain permission denied error.
The code that will trigger the error is inside ajax(): 
`req.open( "GET", url, true );`

So, inside ripCSS(), i added a check. If the `href` starts with `//` then it should manually add the `window.location.protocol` before the actual `href`. 

Bug fixed