Remove nullable=True in models.py which is set by default
Remove nullable=True in models.py which is set by default

Tiny change: nullable=True is set by default, no need to use it explicitly.

Change-Id: I28883f60a0319d4834913fcabe3a3c04410175c2

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