Move ansible puppet code into a module

If the logic is just in a role, it's hard to re-use it in a one-off
manner on the command line. By putting it into a module, we can
run:

  ansible git0* -m puppet

To run puppet on the git farm, for instance.

Also, the file is completely not openstack specific, so do it in
such a way that we can submit it as a module upstream.

Change-Id: I35b2850e02ec5da2b41ad14eec9fd6d5a356bc93