Use python2 explicitly.

In a mixed python2/3 environment where python3 is the default
the code did not work. Using python2 as the interpreter fixes
this problem.

Signed-off-by: Vivenzio Pagliari <vivenzio.pagliari@gmx.de>
Some PEP8 fixes.

Signed-off-by: Vivenzio Pagliari <vivenzio.pagliari@gmx.de>