/usr/bin/env in shebang line

i18n/extract.py

-#!/usr/bin/python
+#!/usr/bin/env python
   
 """
 See https://edx-wiki.atlassian.net/wiki/display/ENG/PO+File+workflow

i18n/generate.py

-#!/usr/bin/python
+#!/usr/bin/env python
 
 """
  See https://edx-wiki.atlassian.net/wiki/display/ENG/PO+File+workflow

i18n/make_dummy.py

-#!/usr/bin/python
+#!/usr/bin/env python
 
 # Generate test translation files from human-readable po files.
 # 

i18n/transifex.py

-#!/usr/bin/python
+#!/usr/bin/env python
 
 import os, sys
 from polib import pofile