Support to configure VMware vCenter VMDK driver cinder volume driver

If set the volume driver as
cinder.volume.drivers.vmware.vmdk.VMwareVcVmdkDriver, we need provide
the vmware configuration in cinder.conf

Implements: blueprint vmwareapi-support
Change-Id: I4ef75636d4a561e371cdab58539d3e32e63ef9b9
Merge "Support to configure VMware vCenter VMDK driver cinder volume driver"