Add XenAPI driver deprecation warning log message
Add XenAPI driver deprecation warning log message

The XenAPI driver does not have running CI and per the schedule,
is slated for deprecation in Icehouse-3. This adds the warning
message to the log to alert admins to this fact, in line with the
others we have been adding for drivers in similiar situations.

Change-Id: Iaff48aaca27d87c600291b8abcc23273a879366a

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