Feature #1739: Do not set last_poll when a VM is deployed
Feature #1739: Detect missing VMs from the Host poll info, and move them to 'unknown'
Feature #1739: All VMs are set to unk if the host poll fails
Feature #1739: When an individual VM poll fails, the VM is set to unk
Feature #1739: Do not update poll info for VMs that should not be in the reported host