RFC: unarchive module and action_plugin

I have a functional, if barely tested, unarchive module ready for interested folks to take a look at:

http://github.com/pileofrogs/ansible_unarchive

It handles gzip, bzip2 & xz compressed as well as uncompressed tar files

It detects if the archive has already been unpacked and returns changed=False appropriately

The readme on github has a lot more notes

Any feedback is awesome

-Dylan

Best place to make sure something gets reviewed would be submit a pull request.

–Michael