Tool for checking unused imports needed

[Zhongyue Luo]

Currently there are some unused imports in the upstream codebase.

************* Module tests.utils
W: 20,0: Unused import subprocess
************* Module tests.unit.test_plugin
W: 18,0: Unused import cfg
************* Module tests.unit.test_notifier
W: 23,0: Unused import rabbit_notifier
************* Module tests.unit.test_version
...

Instead of conducting janitorial cleanups every now and then we should have pylint check for unused imports for each patch.

Therefore adding a python script that executes pylint and a pylint section to tox.ini should prevent unused imports perminantly.

The reason writing a script is for flexible configuration of pylint which would be useful for adding exceptions in the future.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/24882

[Doug Hellmann (doug-hellmann)]

Monty Taylor is working on flake8 support across all projects.

[Zhongyue Luo (zyluo)]

I sent a mail to Monty about his plans with flake8

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/24882
Committed: http://github.com/openstack/oslo-incubator/commit/4bb00aa8f0e7fb7181ffe6299dfd2a31b860e5c1
Submitter: Jenkins
Branch: master

commit 4bb00aa8f0e7fb7181ffe6299dfd2a31b860e5c1
Author: Zhongyue Luo <email address hidden>
Date: Wed Mar 20 15:48:26 2013 +0800

    Adds pylint section in tox.ini to check for unused imports

    Fixes bug #1157597

    Change-Id: I77e0ddb1babf1eec0bb953b8bfa52cd1d415f709