Add task to download and extract a world archive.

[markrcote]

I created an after-install task that downloads and extracts an archived world. The world can be archived in any format supported by ansible's unarchive module, which handily also autodetects the format, so we can download it to a generic, extension-less filename.

I don't have any docs right now, but I can easily whip some up if you're interested in including this in core.

[benwebber]

Thanks. I'm still thinking about how I'd like to bundle task includes with the role.

The next release will focus on adding support for Spigot and Cuberite (in progress). I'll revisit bundling task includes after that, so please hold on for a bit!