postfix: use my pkg instead of internet one

pkg/postfix/docker-entrypoint.sh

@@ -1,13 +1,7 @@
-#!/bin/sh
+#!/bin/bash
 
-set -e
-
-if [ `which unbound-$1 2>/dev/null` ]; then
-  set -- unbound-"$@"
-elif [ ! `which $1 2>/dev/null` ]; then
-  set -- unbound -dv "$@"
-fi
-
-unbound-anchor
+# POSTFIX_var env -> postconf -e var=$POSTFIX_var
+for e in ${!POSTFIX_*} ; do postconf -e "${e:8}=${!e}" ; done
+chown -R postfix:postfix /var/lib/postfix /var/mail /var/spool/postfix
 
 exec "$@"