update shebang to use python2 instead of the distrb prefered

lib/pt_upload.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python2
 # coding: utf-8
 
 import os

lib/yt_upload.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python2
 # coding: utf-8
 # From Youtube samples : https://raw.githubusercontent.com/youtube/api-samples/master/python/upload_video.py  # noqa
 

prismedia_upload.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python2
 # coding: utf-8
 
 """