Fetch doesn't work for subdirectories

[iamdriz]

When using the fetch method to pull down the css or js files it doesn't prefix the path.

For example if I have an app at:

http://domain.com/HelloWorld

and the webroot is here:

domain.com/html/HelloWorld/App/webroot/

So instead of getting:

/HelloWorld/css/shrink_fd92fc8fcce629a200415826e4b96d9c.css

you get:

/css/shrink_fd92fc8fcce629a200415826e4b96d9c.css