metric enhancement - autostart

[Senthil Nathan]

The ability to allow metric collection to auto start when the VM is started. The metric will have to be predefined.

I use metrics to determine how busy the VM is so I can take/kill snapshots for backup purposes.

Also use metrics to monitor and alert if guests are running hot, out of resources, etc.

For the above and more reasons, it would benefit to have a predefined, auto-starting metric.