Added a very basic firewalld module

I didn't know where to place to request inclusion into Ansible 1.3 so I just dropped it into hacking/ for now.

This module implements very basic firewalld management for ports and services.

There are a lot of firewalld features that I'd like to eventually add to this but I don't really know what people care about and this initial functionality is all I really need right now so I'd like at least to get some feedback and plan to include more as time goes on.

Comments and snide remarks welcome. :)