VMware: add tests for image fetch/cache functions
VMware: add tests for image fetch/cache functions

Adds unit tests for the vmops image fetch/prepare/cache functions.
No existing tests are modified.

partial blueprint vmware-spawn-refactor

Change-Id: I913c7f5ecfec586ff79e2bc7ab1969a8824476b5

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