nixos-install: Run in a separate UTS namespace

This prevents the activation script from clobbering our hostname.
nixos-container: Ensure umask 022

Fixes #2585.
jquery-ui: Update to 1.10.4
nixpkgs: Bump libvirt to 1.2.4
rsyncd: default read/write permissions should be nobody:nogroup
Make geoip buildable on any Unix