add service and package support for OpenBSD

I've been using this for a couple months on my OpenBSD boxes and it seems to work fine. I thought I'd submit it for feedback before I end up sitting on it too much longer. :)

A couple things to call out:

1. The Configurate class makes it a bit easier to deal with config files, and I especially like using it with rc.conf.local and the pkg_scripts services list, but no doubt its not for everyone. Its used for enabling and disabling services.
1. I haven't created any service tests yet.
a chef style issue here is that generally we put load_current_resource at the top of provider code after the initialize method  and then we have public methods like remove_package and install_package, and then have a private section which has all the methods which are internal implementation details