Add v3 versions plugin unit test to v2
Add v3 versions plugin unit test to v2

This patch adds v3 versions plugin unit test to v2 for improving
test coverage of v2 API.

Change-Id: I59dedcd31ea011d6eda7ff93d26b941334a67f51

maelnor/nova,mmnelemane/nova,CEG-FYP-OpenStack/scheduler,Yusuke1987/openstack_template,varunarya10/nova_test_latest,eayunstack/nova,vladikr/nova_drafts,cloudbase/nova,dims/nova,shail2810/nova,virtualopensystems/nova,CCI-MOC/nova,blueboxgroup/nova,NeCTAR-RC/nova,TwinkleChawla/nova,watonyweng/nova,kimjaejoong/nova,mahak/nova,bigswitch/nova,saleemjaveds/https-github.com-openstack-nova,Metaswitch/calico-nova,takeshineshiro/nova,scripnichenko/nova,tangfeixiong/nova,redhat-openstack/nova,zhimin711/nova,kimjaejoong/nova,alvarolopez/nova,ted-gould/nova,eonpatapon/nova,takeshineshiro/nova,mikalstill/nova,eonpatapon/nova,BeyondTheClouds/nova,hanlind/nova,alvarolopez/nova,mikalstill/nova,nikesh-mahalka/nova,whitepages/nova,tianweizhang/nova,tudorvio/nova,devendermishrajio/nova_test_latest,redhat-openstack/nova,zaina/nova,orbitfp7/nova,eayunstack/nova,tudorvio/nova,MountainWei/nova,zzicewind/nova,devendermishrajio/nova_test_latest,fnordahl/nova,tealover/nova,Francis-Liu/animated-broccoli,scripnichenko/nova,angdraug/nova,mmnelemane/nova,sebrandon1/nova,BeyondTheClouds/nova,mandeepdhami/nova,barnsnake351/nova,cloudbase/nova,cernops/nova,mahak/nova,JianyuWang/nova,rajalokan/nova,rajalokan/nova,akash1808/nova,phenoxim/nova,devendermishrajio/nova,klmitch/nova,varunarya10/nova_test_latest,phenoxim/nova,cloudbase/nova-virtualbox,badock/nova,akash1808/nova_test_latest,zaina/nova,vmturbo/nova,klmitch/nova,dawnpower/nova,JioCloud/nova_test_latest,gooddata/openstack-nova,JioCloud/nova,barnsnake351/nova,mandeepdhami/nova,joker946/nova,blueboxgroup/nova,petrutlucian94/nova,raildo/nova,edulramirez/nova,vmturbo/nova,openstack/nova,affo/nova,fnordahl/nova,vmturbo/nova,tianweizhang/nova,whitepages/nova,openstack/nova,akash1808/nova_test_latest,Tehsmash/nova,orbitfp7/nova,jianghuaw/nova,TwinkleChawla/nova,hanlind/nova,raildo/nova,Juniper/nova,thomasem/nova,jeffrey4l/nova,vladikr/nova_drafts,shail2810/nova,jianghuaw/nova,CloudServer/nova,klmitch/nova,rahulunair/nova,isyippee/nova,JianyuWang/nova,JioCloud/nova_test_latest,CEG-FYP-OpenStack/scheduler,yatinkumbhare/openstack-nova,tangfeixiong/nova,rajalokan/nova,isyippee/nova,berrange/nova,jianghuaw/nova,gooddata/openstack-nova,badock/nova,rajalokan/nova,virtualopensystems/nova,belmiromoreira/nova,iuliat/nova,jianghuaw/nova,maelnor/nova,edulramirez/nova,NeCTAR-RC/nova,apporc/nova,Tehsmash/nova,apporc/nova,gooddata/openstack-nova,silenceli/nova,bgxavier/nova,yosshy/nova,tealover/nova,felixma/nova,bgxavier/nova,felixma/nova,ted-gould/nova,saleemjaveds/https-github.com-openstack-nova,devendermishrajio/nova,nikesh-mahalka/nova,vmturbo/nova,double12gzh/nova,thomasem/nova,sebrandon1/nova,projectcalico/calico-nova,CCI-MOC/nova,Stavitsky/nova,klmitch/nova,Juniper/nova,adelina-t/nova,cyx1231st/nova,alaski/nova,rahulunair/nova,adelina-t/nova,hanlind/nova,j-carpentier/nova,petrutlucian94/nova,bigswitch/nova,silenceli/nova,Stavitsky/nova,LoHChina/nova,affo/nova,Francis-Liu/animated-broccoli,jeffrey4l/nova,Juniper/nova,zzicewind/nova,rahulunair/nova,JioCloud/nova,alaski/nova,alexandrucoman/vbox-nova-driver,mikalstill/nova,noironetworks/nova,BeyondTheClouds/nova,berrange/nova,cernops/nova,CloudServer/nova,double12gzh/nova,watonyweng/nova,cyx1231st/nova,j-carpentier/nova,ruslanloman/nova,dims/nova,LoHChina/nova,sebrandon1/nova,Metaswitch/calico-nova,yosshy/nova,MountainWei/nova,mgagne/nova,gooddata/openstack-nova,akash1808/nova,cloudbase/nova-virtualbox,ruslanloman/nova,noironetworks/nova,cernops/nova,belmiromoreira/nova,dawnpower/nova,cloudbase/nova,joker946/nova,angdraug/nova,projectcalico/calico-nova,iuliat/nova,mahak/nova,mgagne/nova,alexandrucoman/vbox-nova-driver,Yusuke1987/openstack_template,zhimin711/nova,yatinkumbhare/openstack-nova,Juniper/nova,openstack/nova