use new s6-rc layout

rootfs/etc/cont-init.d/02-static-user

@@ -1,14 +0,0 @@
-#!/usr/bin/with-contenv sh
-
-if [ ! -z ${STATIC_USER+x} ]; then
-    echo ${STATIC_PASSWORD} | ftpasswd \
-        --sha512 \
-        --passwd \
-        --home /var/lib/ftp/data \
-        --uid "2222" \
-        --gid "2222" \
-        --name "$STATIC_USER" \
-        --shell /bin/sh \
-        --file /etc/proftpd/passwd \
-        --stdin
-fi