python: Use explicit integer divisions

python: Use explicit integer divisions

In Python 2, divisions of integers return an integer:

    >>> 32 / 4
    8

In Python 3 though, they return floats:

    >>> 32 / 4
    8.0

However, Python 3 has an explicit integer division operator:

    >>> 32 // 4
    8

That operator exists on Python >= 2.2, so let's use it everywhere to
make the scripts compatible with both Python 2 and 3.

In addition, using __future__.division tells Python 2 to behave the same
way as Python 3, which helps ensure the scripts produce the same output
in both versions of Python.

Signed-off-by: Mathieu Bridon <bochecha@daitauha.fr>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com> (v2)
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>