Add OpenStack trove classifier for PyPI

Add trove classifier to have the client listed among the
other OpenStack-related projets on PyPI.

Change-Id: I34c47bde5885a3f436c100cda5202d6ad8356131
Signed-off-by: Doug Hellmann <doug.hellmann@dreamhost.com>

setup.py

@@ -42,6 +42,7 @@ setuptools.setup(
     classifiers=[
        'Development Status :: 2 - Pre-Alpha',
        'Environment :: Console',
+       'Environment :: OpenStack',
        'Intended Audience :: Developers',
        'Intended Audience :: Information Technology',
        'License :: OSI Approved :: Apache Software License',