Archlinux support

This adds support for Arch Linux/Arch Linux ARM. It has been around in my repo for a long time now, with a good number of users I believe, and rarely has issues.

First 3 commits are not directly related to arch, but necessary (especially the last 2).
Rather than using example.com (which exists), how about [http://192.0.2.1/](http://tools.ietf.org/html/rfc5737)?