Problem: python shebang in py modules that are not executable

[sevein]

We only need to have a shebang if the script is an executable / entry point.

699b018046afba3aaac48356adfb2e2a70b2a075 introduced shebags in modules where I believe it's not needed.

> transfers/amclientargs.py:1:#!/usr/bin/env python
> transfers/defaults.py:1:#!/usr/bin/env python
> transfers/errors.py:1:#!/usr/bin/env python
> transfers/loggingconfig.py:1:#!/usr/bin/env python
> transfers/utils.py:1:#!/usr/bin/env python