Add systemd support and start updating archlinux stuff

Arch Linux switched to systemd some time ago, unfortunately rackspace and open stack are behind. This patch provides a systemd.service unit to be installed on Arch Linux images, it should also work for fedora and anyone else that booted with systemd.

I just started working at rackspace last week, (A8 first shift) but I would really like to know how I can get my hands on that Arch Linux image that still defaults to initscripts so I can bring it up to date and also learn more about openstack and nova-agent and the json rest api.

I am also working on a small set of patches for the switch to netctl since we also just dropped netcfg from the repositories to the aur today.

https://www.archlinux.org/trustedusers/#dwallace

Thanks