add debconf template and fix sed

DEBIAN/postinst

@@ -1,6 +1,10 @@
-#!/bin/sh
+#!/bin/bash
+set -e
 
-# Script executado pós instalação
-# systemctl restart nscd
-PASS=$(whiptail --passwordbox "Senha do LDAP" 10 50)
-sed -i 's/BINDPW/$PASS/' /etc/sssd/sssd.conf
+. /usr/share/debconf/confmodule
+
+db_get alice-auth/ldap-bind-password
+LDAP_BIND_PASSWORD="$RET"
+CONFIG=/etc/sssd/sssd.conf
+
+sed -i "s/ldap_default_authtok =.*/ldap_default_authtok = $LDAP_BIND_PASSWORD/" $CONFIG