Add the external gateway interface to vpn router
Add the external gateway interface to vpn router

Change-Id: Ib24080f0895a322576c837566976ade9fc4d8069
Closes-Bug: #1258379

JioCloud/tempest,CiscoSystems/tempest,Lilywei123/tempest,pczerkas/tempest,BeenzSyed/tempest,neerja28/Tempest,afaheem88/tempest_neutron,cloudbase/lis-tempest,armando-migliaccio/tempest,cisco-openstack/tempest,tudorvio/tempest,vmahuli/tempest,akash1808/tempest,danielmellado/tempest,eggmaster/tempest,jaspreetw/tempest,ntymtsiv/tempest,varunarya10/tempest,Vaidyanath/tempest,roopali8/tempest,alinbalutoiu/tempest,bigswitch/tempest,roopali8/tempest,rzarzynski/tempest,dkalashnik/tempest,manasi24/jiocloud-tempest-qatempest,xbezdick/tempest,redhat-cip/tempest,izadorozhna/tempest,pandeyop/tempest,manasi24/jiocloud-tempest-qatempest,Juniper/tempest,LIS/lis-tempest,CiscoSystems/tempest,hayderimran7/tempest,eggmaster/tempest,JioCloud/tempest,BeenzSyed/tempest,hayderimran7/tempest,pczerkas/tempest,Juraci/tempest,vedujoshi/tempest,jaspreetw/tempest,FujitsuEnablingSoftwareTechnologyGmbH/tempest,bigswitch/tempest,queria/my-tempest,yamt/tempest,izadorozhna/tempest,manasi24/tempest,NexusIS/tempest,flyingfish007/tempest,openstack/tempest,openstack/tempest,Mirantis/tempest,queria/my-tempest,nunogt/tempest,Tesora/tesora-tempest,manasi24/tempest,cisco-openstack/tempest,sebrandon1/tempest,danielmellado/tempest,afaheem88/tempest,pandeyop/tempest,NexusIS/tempest,neerja28/Tempest,armando-migliaccio/tempest,afaheem88/tempest_neutron,redhat-cip/tempest,vedujoshi/os_tempest,ebagdasa/tempest,vmahuli/tempest,jamielennox/tempest,ebagdasa/tempest,Mirantis/tempest,jamielennox/tempest,flyingfish007/tempest,FujitsuEnablingSoftwareTechnologyGmbH/tempest,hpcloud-mon/tempest,Vaidyanath/tempest,yamt/tempest,zsoltdudas/lis-tempest,rzarzynski/tempest,akash1808/tempest,tonyli71/tempest,tudorvio/tempest,xbezdick/tempest,cloudbase/lis-tempest,Juniper/tempest,rakeshmi/tempest,masayukig/tempest,zsoltdudas/lis-tempest,vedujoshi/tempest,dkalashnik/tempest,nunogt/tempest,afaheem88/tempest,masayukig/tempest,Lilywei123/tempest,rakeshmi/tempest,vedujoshi/os_tempest,tonyli71/tempest,alinbalutoiu/tempest,Tesora/tesora-tempest,varunarya10/tempest,LIS/lis-tempest,sebrandon1/tempest,ntymtsiv/tempest,Juraci/tempest,hpcloud-mon/tempest