busybox

Move several applets to different install dir:

Moved to [/usr]/sbin:
addgroup, adduser, delgroup, deluser,
arping, chat, ether-wake, fdformat, ifplugd,
ip, ipaddr, iplink, iproute, iprule, iptunnel,
killall5, readahead, rtcwake, tftpd, add-shell, remove-shell, powertop.

Moved to /bin for /usr/bin: kbd_mode.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>