Correct the shebangs to !/usr/bin/env python2.7

Since we require Python 2.7, we need to tell the Python interpreter so.
This will cause any confusion and it will hopefully make packager's life
easier. Also, we need to use the /usr/bin/env, because we can not assume
that Python will be available at /usr/bin/python. A very good answer at
SO:

    http://stackoverflow.com/a/19305076/1105870

Signed-off-by: Ignas Anikevicius (gns_ank) <anikevicius@gmail.com>
Use print and unicode from future

This will make it easier to port everything to Py3k. And we can do this,
because all these feature should be in Python 2.7, which we require.

Signed-off-by: Ignas Anikevicius (gns_ank) <anikevicius@gmail.com>