Make non-admin users can unshelve a server
Make non-admin users can unshelve a server

If non-admin users try to unshelve a server, nova-compute fails due to
"User does not have admin privileges" while getting hypervisor_hostname.
This patch changes the user context to admin's one temporarily to get the
hypervisor_hostname.

Closes-Bug: 1245312
Change-Id: I84dce1f7694d09c1281da13c6008bb3aa5940f85

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