Including a jar directly in your repository is... not exactly the best approach, and definitely not easy to maintain for you and your users. Chances are most people won't bother to include this in their projects without Maven/Gradle support. (Full disclosure: I haven't checked out your library in action yet.)
I'd start with moving the jar to the releases section and then uploading it to Maven Central. Finally, you could try to add this as a third-party extension to the gdx-setup.