py3kcompat: remove in python-ceilometerclient

Everything is already in six>=1.4.0 and we already depend on such a
version. There's no reason to keep this file. So remove py3kcompat
from python-ceilometerclient.

Change-Id: Ide6876e7a60377cb3843816d1d9ab2c589bc8f1b
Closes-Bug: #1280033
Updated from global requirements

Change-Id: I743b87c111923105b7cb5cc357f363812bfd0358
Merge "py3kcompat: remove in python-ceilometerclient"