Add Environment::OpenStack classifier

Doug had this registered for us:

  http://mail.python.org/pipermail/catalog-sig/2012-October/004634.html

It makes it easier to find all OpenStack packages.

Change-Id: I17ee76616eb11a02a65b7a624f625a207b9e9631

setup.py

@@ -35,6 +35,7 @@ setuptools.setup(
                      'line arguments and .ini style configuration files.',
     classifiers=[
         'Development Status :: 4 - Beta',
+        'Environment :: OpenStack',
         'License :: OSI Approved :: Apache Software License',
         'Operating System :: POSIX :: Linux',
         'Programming Language :: Python :: 2.6', ],