NzbDrone v1533 - Added SPK compatibility for built-in NzbDrone updates!

SPK now versioned by date for multi-branch and built-in NzbDrone updater compatibility - SPK upgrade now retains current NzbDrone binary (avoids potential binary downgrade) when necessary
Why not use latest when building the package then? Like described [here](https://github.com/NzbDrone/NzbDrone/wiki/Installation#other)