Changed a little bit, for way better performance if you don't use pathfinder. You can download the pre-compiled app here

For the original script and readme, look into the master branch

If you are running Yosemite or higher you can not just drag an app to your Finder Toolbar. In Yosemite you need to hold command and drag the app to the Finder Toolbar for it to "install". Open-in-sublime falls under this category. Reference from Mac OS X Hints.