Add 'vm.guest.disk.discover' method for discovering disks on all
VirtualMachine managed objects
Remove 'vm.datastore.discover' method as we already provide methods for
getting the datastores used by a VM and discovery of datastores + polling
New method for discovering VM guest disks is 'vm.disk.discover'
Add 'vm.disk.get' method for collecting properties for a single disk
path in a Virtual Machine