Fixes Issue #116: Modify rsync to return the paths synced in the patch method

Rsync now returns a list of paths that it has patched in the final step of rsync i.e. patch
The easiest fix here is to pass the callback along with your call to `handleError`:

```js
function handleError(err, callback) {
  ...
  callback(err);
}

...
// Now callers do this:
if(err) {
  return handleError(err, callback);
}
```