Split out part of compute's init_host.
Split out part of compute's init_host.

The init_host() function in the compute manager has grown a good bit.
The amount of nesting for instance initialization was pretty deep,
making it a bit ugly.  This patch splits out the code for initializing
an instance during the service initialization and puts it into its own
function, making things a bit more readable.

Change-Id: I5183baa76304bfc04af3c7347218eefbc3dc84e3

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