Add Python 3 classifiers
Add Python 3 classifiers

Change-Id: Ib22c48ce091916c7c874db91c8c16ebfc7846411

cryptickp/python-neutronclient,venusource/python-neutronclient,huntxu/python-neutronclient,johnpbatty/python-neutronclient,openstack/python-neutronclient,eayunstack/python-neutronclient,noironetworks/python-neutronclient,Stavitsky/python-neutronclient,roaet/python-neutronclient,rackerlabs/rackspace-python-neutronclient,rackerlabs/rackspace-python-neutronclient,cernops/python-neutronclient,Stavitsky/python-neutronclient,roaet/python-neutronclient,venusource/python-neutronclient,eayunstack/python-neutronclient,johnpbatty/python-neutronclient,NeCTAR-RC/python-neutronclient,noironetworks/python-neutronclient,Juniper/python-neutronclient,mangelajo/python-neutronclient,huntxu/python-neutronclient,Juniper/python-neutronclient,NeCTAR-RC/python-neutronclient,mangelajo/python-neutronclient,cryptickp/python-neutronclient,openstack/python-neutronclient,cernops/python-neutronclient