Hyper-V support for WMI root\virtualization\v2 namespace

The Neutron Hyper-V plugin agent uses the WMI API to execute most OS actions.

Starting from Windows Server 2008 and up to Windows Server 2008 R2 the namespace used for hypervisor management was "root\virtualization" (aka V1). Windows Server 2012 introduced a refactored namespace "root\virtualization\v2", offering also the V1 version for backwards compatibility with existing tools.

The object of this blueprint is to add utils classes implementing the V2 namespace without impacting on the ops classes. This will be accomplished by adding an abstract base class for each utils class, providing the current V1 implementations along with a V2 versions. Factory methods will instantiate the proper class at run time based on the OS version (OS <= 2008 R2: V1, OS >= 2012: V2).

Note: Hyper-V 2012 R2 (scheduled for this year, preview available for download now) drops support for the V1 namespace, which means that the currently available code (Grizzly) will NOT be supported.