Don't warn up front about libvirt loading issues in NWFilterFirewall
Don't warn up front about libvirt loading issues in NWFilterFirewall

Use the same technique as in libvirt/driver.py to delay import of
libvirt module

Change-Id: I500ddde4651f0f747c54533a1a308eee5a87f717

mgagne/nova,rajalokan/nova,alaski/nova,raildo/nova,qwefi/nova,apporc/nova,petrutlucian94/nova_dev,zzicewind/nova,Stavitsky/nova,devendermishrajio/nova_test_latest,mgagne/nova,shahar-stratoscale/nova,varunarya10/nova_test_latest,Brocade-OpenSource/OpenStack-DNRM-Nova,Metaswitch/calico-nova,cloudbau/nova,akash1808/nova_test_latest,orbitfp7/nova,bigswitch/nova,CiscoSystems/nova,Juniper/nova,watonyweng/nova,openstack/nova,eonpatapon/nova,tudorvio/nova,joker946/nova,bclau/nova,maheshp/novatest,Triv90/Nova,affo/nova,rickerc/nova_audit,cyx1231st/nova,leilihh/novaha,Yuriy-Leonov/nova,Metaswitch/calico-nova,gspilio/nova,eharney/nova,rickerc/nova_audit,cernops/nova,maheshp/novatest,leilihh/nova,virtualopensystems/nova,j-carpentier/nova,JioCloud/nova,CloudServer/nova,sebrandon1/nova,JianyuWang/nova,alvarolopez/nova,CloudServer/nova,sridevikoushik31/nova,tangfeixiong/nova,BeyondTheClouds/nova,TieWei/nova,mandeepdhami/nova,kimjaejoong/nova,TieWei/nova,gooddata/openstack-nova,whitepages/nova,Tehsmash/nova,gooddata/openstack-nova,ntt-sic/nova,sacharya/nova,leilihh/novaha,Brocade-OpenSource/OpenStack-DNRM-Nova,nikesh-mahalka/nova,Francis-Liu/animated-broccoli,dawnpower/nova,rahulunair/nova,TwinkleChawla/nova,jianghuaw/nova,devendermishrajio/nova_test_latest,eharney/nova,thomasem/nova,BeyondTheClouds/nova,NeCTAR-RC/nova,ewindisch/nova,ruslanloman/nova,tudorvio/nova,angdraug/nova,cloudbase/nova,phenoxim/nova,sebrandon1/nova,maelnor/nova,silenceli/nova,kimjaejoong/nova,joker946/nova,adelina-t/nova,bigswitch/nova,Juniper/nova,luogangyi/bcec-nova,imsplitbit/nova,barnsnake351/nova,varunarya10/nova_test_latest,vmturbo/nova,hanlind/nova,MountainWei/nova,j-carpentier/nova,takeshineshiro/nova,mahak/nova,mikalstill/nova,DirectXMan12/nova-hacking,luogangyi/bcec-nova,vmturbo/nova,Triv90/Nova,klmitch/nova,takeshineshiro/nova,jianghuaw/nova,hanlind/nova,scripnichenko/nova,saleemjaveds/https-github.com-openstack-nova,badock/nova,CiscoSystems/nova,tealover/nova,Yusuke1987/openstack_template,tealover/nova,blueboxgroup/nova,gooddata/openstack-nova,angdraug/nova,JioCloud/nova_test_latest,maheshp/novatest,eayunstack/nova,rrader/nova-docker-plugin,OpenAcademy-OpenStack/nova-scheduler,plumgrid/plumgrid-nova,fnordahl/nova,iuliat/nova,CCI-MOC/nova,edulramirez/nova,rajalokan/nova,SUSE-Cloud/nova,raildo/nova,Francis-Liu/animated-broccoli,badock/nova,CCI-MOC/nova,Tehsmash/nova,projectcalico/calico-nova,fnordahl/nova,felixma/nova,cloudbase/nova-virtualbox,SUSE-Cloud/nova,virtualopensystems/nova,zzicewind/nova,watonyweng/nova,yosshy/nova,shail2810/nova,citrix-openstack-build/nova,tanglei528/nova,double12gzh/nova,Triv90/Nova,dims/nova,vladikr/nova_drafts,thomasem/nova,LoHChina/nova,plumgrid/plumgrid-nova,phenoxim/nova,mikalstill/nova,Yuriy-Leonov/nova,sridevikoushik31/openstack,sacharya/nova,JioCloud/nova_test_latest,LoHChina/nova,jianghuaw/nova,tianweizhang/nova,cernops/nova,ruslanloman/nova,bgxavier/nova,dstroppa/openstack-smartos-nova-grizzly,edulramirez/nova,akash1808/nova,projectcalico/calico-nova,BeyondTheClouds/nova,ntt-sic/nova,redhat-openstack/nova,belmiromoreira/nova,yatinkumbhare/openstack-nova,yatinkumbhare/openstack-nova,klmitch/nova,ted-gould/nova,rahulunair/nova,Stavitsky/nova,mmnelemane/nova,sridevikoushik31/openstack,jianghuaw/nova,dims/nova,affo/nova,sridevikoushik31/nova,yrobla/nova,cernops/nova,sridevikoushik31/openstack,Juniper/nova,zaina/nova,silenceli/nova,sridevikoushik31/nova,gspilio/nova,DirectXMan12/nova-hacking,petrutlucian94/nova,akash1808/nova_test_latest,bclau/nova,petrutlucian94/nova,ewindisch/nova,openstack/nova,shootstar/novatest,tangfeixiong/nova,Yusuke1987/openstack_template,noironetworks/nova,qwefi/nova,JioCloud/nova,felixma/nova,jeffrey4l/nova,CEG-FYP-OpenStack/scheduler,alexandrucoman/vbox-nova-driver,alaski/nova,double12gzh/nova,devendermishrajio/nova,gspilio/nova,cloudbase/nova,cloudbau/nova,isyippee/nova,ted-gould/nova,sebrandon1/nova,scripnichenko/nova,cloudbase/nova-virtualbox,devendermishrajio/nova,whitepages/nova,mmnelemane/nova,klmitch/nova,mandeepdhami/nova,vmturbo/nova,sridevikoushik31/nova,devoid/nova,nikesh-mahalka/nova,shahar-stratoscale/nova,rrader/nova-docker-plugin,Juniper/nova,berrange/nova,mikalstill/nova,shail2810/nova,tianweizhang/nova,saleemjaveds/https-github.com-openstack-nova,tanglei528/nova,leilihh/nova,vladikr/nova_drafts,berrange/nova,gooddata/openstack-nova,DirectXMan12/nova-hacking,spring-week-topos/nova-week,JianyuWang/nova,rajalokan/nova,klmitch/nova,iuliat/nova,eonpatapon/nova,jeffrey4l/nova,dstroppa/openstack-smartos-nova-grizzly,alvarolopez/nova,spring-week-topos/nova-week,mahak/nova,CEG-FYP-OpenStack/scheduler,zhimin711/nova,cloudbase/nova,barnsnake351/nova,redhat-openstack/nova,zhimin711/nova,orbitfp7/nova,yosshy/nova,openstack/nova,imsplitbit/nova,alexandrucoman/vbox-nova-driver,dawnpower/nova,bgxavier/nova,belmiromoreira/nova,cyx1231st/nova,hanlind/nova,apporc/nova,petrutlucian94/nova_dev,akash1808/nova,shootstar/novatest,yrobla/nova,devoid/nova,isyippee/nova,rajalokan/nova,OpenAcademy-OpenStack/nova-scheduler,rahulunair/nova,zaina/nova,viggates/nova,vmturbo/nova,blueboxgroup/nova,dstroppa/openstack-smartos-nova-grizzly,noironetworks/nova,eayunstack/nova,MountainWei/nova,adelina-t/nova,maelnor/nova,TwinkleChawla/nova,NeCTAR-RC/nova,mahak/nova,yrobla/nova,viggates/nova,citrix-openstack-build/nova