Hyper-V: enable instance new metrics

Windows Hyper-V / Server 2012 R2 introduced new instance metrics that can be collected (e.g.: Disk Latency, Disk IOPS, memory usage). After the instance has been spawned, those metrics must be enabled for collection, otherwise ceilometer will not be able to collect them. Those metrics can give us an overview of the instance's performance.

Currently, the HyperVDriver enables collection of CPU, disk read / write and network read / write metrics. The metrics with following Captions must be enabled, after an instance is spawned:
Average Disk Latency
Average Normalized Disk Throughput
Aggregated Average Memory Utilization