add org-auto-tangle to NonGNU ELPA

[Yilkal Argaw]

org-auto-tangle is a package that does what it says on its name it
automatically and asynchronously tangles org files on save if the org
file has the #+auto_tangle  option set to true. I am the creator and
maintainer of the package and I am willing to maintain it for the
future. I thought it might be useful to users that use org files for
their init.