I haven't seen one, but all you have to do is to package a VIJava.jar as an osgi bundle with bundlor tool. Checkout FAQ section on How to package a lib as an OSGI bundle. The advantage of generating own is that you can tag your own versioning scheme and use it across all your extension modules and your build infrastructure.
There is also a much easier to use tool for creating osgi bundles. It's called "bnd" (http://www.aqute.biz/Bnd/Bnd). For example, to create vijava bundles:
java -jar bnd-2.2.0.jar wrap -o dom4j-1.6.1.jar ../dom4j-1.6.1.jar
java -jar bnd-2.2.0.jar wrap -o vijava-55.jar vijava55b20130927.jar
Note that vijava exports the same namespace as vim25.jar package. You may need to remove vim25.jar from serenity server library path while you're developing/testing.
That is right. As the creator of the vijava API, I am not aware of it's downloadable anywhere. But as vSphereArt pointed out, it's easy to create one yourself.