Use autocloseable and build on github

[schup]

Looking into getting a NFC based audiobook player for my kids and had a look how I could add that to AudioAnchor.

I have no experience with Android and used to code to get some familiarity and starting points.

This PR contains a few code simplifications and adds auto closable to make sure resources are also closed on errors. I've added an initial build on github to verify the build is at least building.

Thanks for your work on AudioAnchor.