Missed aufs module in mkinitcpio install script

Signed-off-by: Aaron Griffin <aaronmgriffin@gmail.com>

archiso/install/archiso

 install ()
 {
-    MODULES="cdrom ide-cd_mod ide-core ide-generic unionfs squashfs isofs loop $(all_modules '/kernel/fs' | grep -v "nls") "
+    MODULES="cdrom ide-cd_mod ide-core ide-generic aufs squashfs isofs loop $(all_modules '/kernel/fs' | grep -v "nls") "
     MODULES="${MODULES} $(checked_modules "/usb/host" | grep -ve "_cs" -e "sl1811-hcd" -e "isp116x-hcd")"
     MODULES=$(echo ${MODULES}) #trim whitespace
     if [ "x${MODULES}" != "x" ]; then