Using redis keys to store clone timestamps will allow for a global TTL
for VMs in the 'pending' pool; failed clones should be cleaned up and
retried after a set period of time (eg. 15m).
Previous, the propertyCollector method was used to find VMs within
vCenter. This method was ineffecient, as it would retrieve a list of
the entire vCenter inventory and then parse for the specified VM. This
has been replaced with a fetch via searchIndex.FindByDnsName, which
returns only the requested VM object.
