Make shebang consistent with ovpn scripts

'/usr/bin/env python' also does not set useful process name for start-stop-daemon

re6st-conf

-#!/usr/bin/env python
+#!/usr/bin/python
 import argparse, atexit, errno, os, subprocess, sqlite3, sys, xmlrpclib
 from OpenSSL import crypto
 from re6st import utils

re6st-registry

-#!/usr/bin/env python
+#!/usr/bin/python
 import errno, logging, mailbox, os, random, select
 import smtplib, socket, sqlite3, string, subprocess, sys
 import threading, time, traceback, xmlrpclib

re6stnet

-#!/usr/bin/env python
+#!/usr/bin/python
 import atexit, errno, logging, os, select, signal
 import sqlite3, subprocess, sys, time, traceback
 from re6st import plib, utils, db, tunnel