conf: improve libvirt lvm
conf: improve libvirt lvm

Change-Id: Iacc36b425a67fd340a7c545c31c1be180940ff04
Implements: blueprint centralize-config-options-ocata

hanlind/nova,klmitch/nova,mahak/nova,openstack/nova,rajalokan/nova,rajalokan/nova,klmitch/nova,gooddata/openstack-nova,hanlind/nova,jianghuaw/nova,vmturbo/nova,vmturbo/nova,klmitch/nova,klmitch/nova,gooddata/openstack-nova,openstack/nova,mikalstill/nova,rajalokan/nova,mikalstill/nova,Juniper/nova,rahulunair/nova,rahulunair/nova,vmturbo/nova,mahak/nova,rahulunair/nova,jianghuaw/nova,gooddata/openstack-nova,phenoxim/nova,mikalstill/nova,phenoxim/nova,jianghuaw/nova,gooddata/openstack-nova,Juniper/nova,jianghuaw/nova,rajalokan/nova,vmturbo/nova,hanlind/nova,mahak/nova,Juniper/nova,Juniper/nova,openstack/nova