nicer file header for executable files.

src/history_manager.py

-#! /usr/bin/env python
+#!/bin/sh
+''':'
+exec python -OOt "$0"
+' '''
 ## history_manager.py
 ##
 ## Copyright (C) 2006 Nikos Kouremenos <kourem@gmail.com>

src/migrate_logs_to_dot9_db.py

-#!/usr/bin/env python
+#!/bin/sh
+''':'
+exec python -OOt "$0"
+' '''
 ## Contributors for this file:
 ## - Yann Le Boulanger <asterix@lagaule.org>
 ## - Nikos Kouremenos <kourem@gmail.com>