Allow ML2 plugin test cases to be run independently
Allow ML2 plugin test cases to be run independently

Some test cases in neutron.tests.unit.ml2.test_ml2_plugin override the
network_vlan_ranges option in the ml2_type_vlan config group. However,
the test module does not import the ML2 type driver module where this
config group's options are registered. When unit tests are run by
tox/testr the module is imported during test discovery. Running the
tests independently via nose or testtools requires the option to be
explicitly imported.

Change-Id: I355a2d1212992eafed44f6d843c0fc9deb665df7
Closes-bug: #1287792

leeseuljeong/leeseulstack_neutron,Metaswitch/calico-neutron,alexandrucoman/vbox-neutron-agent,vbannai/neutron,wolverineav/neutron,mattt416/neutron,huntxu/neutron,igor-toga/local-snat,vbannai/neutron,yanheven/neutron,silenci/neutron,waltBB/neutron_read,leeseuljeong/leeseulstack_neutron,skyddv/neutron,yuewko/neutron,takeshineshiro/neutron,asgard-lab/neutron,takeshineshiro/neutron,cernops/neutron,watonyweng/neutron,cloudbase/neutron,jumpojoy/neutron,mandeepdhami/neutron,noironetworks/neutron,CiscoSystems/neutron,Stavitsky/neutron,CiscoSystems/neutron,chitr/neutron,projectcalico/calico-neutron,projectcalico/calico-neutron,glove747/liberty-neutron,glove747/liberty-neutron,watonyweng/neutron,shahbazn/neutron,openstack/neutron,cloudbase/neutron,sebrandon1/neutron,suneeth51/neutron,apporc/neutron,gopal1cloud/neutron,gkotton/neutron,mahak/neutron,yuewko/neutron,sasukeh/neutron,skyddv/neutron,pnavarro/neutron,SamYaple/neutron,vveerava/Openstack,aristanetworks/neutron,alexandrucoman/vbox-neutron-agent,openstack/neutron,mmnelemane/neutron,JianyuWang/neutron,dims/neutron,cisco-openstack/neutron,adelina-t/neutron,apporc/neutron,javaos74/neutron,paninetworks/neutron,blueboxgroup/neutron,redhat-openstack/neutron,mandeepdhami/neutron,rdo-management/neutron,pnavarro/neutron,dhanunjaya/neutron,SamYaple/neutron,huntxu/neutron,virtualopensystems/neutron,yamahata/tacker,Metaswitch/calico-neutron,aristanetworks/neutron,eayunstack/neutron,mahak/neutron,JianyuWang/neutron,antonioUnina/neutron,blueboxgroup/neutron,yamahata/tacker,swdream/neutron,sasukeh/neutron,gopal1cloud/neutron,blueboxgroup/neutron,CiscoSystems/neutron,vivekanand1101/neutron,yamahata/tacker,yanheven/neutron,paninetworks/neutron,cernops/neutron,mmnelemane/neutron,gkotton/neutron,SmartInfrastructures/neutron,MaximNevrov/neutron,barnsnake351/neutron,NeCTAR-RC/neutron,barnsnake351/neutron,wolverineav/neutron,adelina-t/neutron,leeseuljeong/leeseulstack_neutron,cloudbase/neutron-virtualbox,JioCloud/neutron,swdream/neutron,klmitch/neutron,rdo-management/neutron,eayunstack/neutron,bgxavier/neutron,wenhuizhang/neutron,vivekanand1101/neutron,noironetworks/neutron,bigswitch/neutron,virtualopensystems/neutron,SmartInfrastructures/neutron,vbannai/neutron,wenhuizhang/neutron,JioCloud/neutron,neoareslinux/neutron,cloudbase/neutron-virtualbox,dhanunjaya/neutron,miyakz1192/neutron,virtualopensystems/neutron,infobloxopen/neutron,miyakz1192/neutron,openstack/neutron,jacknjzhou/neutron,asgard-lab/neutron,jumpojoy/neutron,silenci/neutron,jerryz1982/neutron,bgxavier/neutron,bigswitch/neutron,dims/neutron,leeseulstack/openstack,sebrandon1/neutron,javaos74/neutron,eonpatapon/neutron,antonioUnina/neutron,gkotton/neutron,neoareslinux/neutron,jacknjzhou/neutron,leeseulstack/openstack,magic0704/neutron,infobloxopen/neutron,suneeth51/neutron,waltBB/neutron_read,igor-toga/local-snat,redhat-openstack/neutron,vveerava/Openstack,chitr/neutron,jerryz1982/neutron,klmitch/neutron,leeseulstack/openstack,MaximNevrov/neutron,magic0704/neutron,vveerava/Openstack,NeCTAR-RC/neutron,Stavitsky/neutron,mattt416/neutron,cisco-openstack/neutron,shahbazn/neutron,eonpatapon/neutron,mahak/neutron