avocado/utils/partition.py: remove interpreter

This utilility library file has no business at being executable,
so let's remote the executable interpreter currently set.

This fixes the following two errors spotted by rpmlint:

   E: wrong-script-interpreter
   /usr/lib/python2.7/site-packages/avocado/utils/partition.py
   /usr/bin/env python
   E: non-executable-script
   /usr/lib/python2.7/site-packages/avocado/utils/partition.py 644
   /usr/bin/env python
Signed-off-by: NCleber Rosa <crosa@redhat.com>

avocado/utils/partition.py

-#!/usr/bin/env python
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation; either version 2 of the License, or