Raise an error if module import fails.
Raise an error if module import fails.

Previously a missing module would cause the config file generator
to pass (mostly) silently with only a small message going to
stdout. If we can't import a module that seems like it is a bad
thing so lets just bail.

Change-Id: I391220e1344ba1785bf04654c7c5f52e2e8e82fc

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