Merge pull request #136 from dougm/device-helpers

New device helpers and cli commands
Fix import.ova command

Fixes github issue #135
Merge pull request #137 from dougm/ova

Fix import.ova command
Add Upload.Headers field

Supports adding arbitrary HTTP headers to upload requests.
Support non-disk files in import.ovf

Fixes github issue #134
Fix import.ovf with relative ovf source path
Merge pull request #138 from dougm/ova

Support non-disk files in import.ovf
Add VirtualMachineList.PrimaryMacAddress helper
Output MAC Address in device.info