Sync to newer openstack.common.cfg
Sync to newer openstack.common.cfg

Changes since last sync are:

 * New ConfigOpts.find_file() for locating conf files
 * Support for directory source of config files
 * Provide file extension when when looking for files
 * Some refactoring of the cfg cache
 * Add caching to openstack.common.cfg

Change-Id: I5fd483b8d1a6e83f7237507132009d31dd8bcb77

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