Hotfix: Roll back an attempt to let the system know we want Python 2. Its better to make the uploader Python 3 compatible

Tools/px_mkfw.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 ############################################################################
 #
 #   Copyright (C) 2012 PX4 Development Team. All rights reserved.

Tools/px_uploader.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 ############################################################################
 #
 #   Copyright (C) 2012 PX4 Development Team. All rights reserved.