Merge pull request #161 from dougm/device-helpers

Improve SCSI controller support
Move environment variables names into constants
Don't run datastore.rm if there is no input
Check minimum API version from client flag
Merge pull request #162 from pietern/govc-version-check

govc version check
Work on README
Merge pull request #163 from pietern/readme

Work on README
Add VM power ops

Suspend, ShutdownGuest and RebootGuest
Add new ops to vm.power command
Don't run vm.destroy if there is no input
Merge pull request #164 from dougm/vm-power

Add VM power ops
Add CreateEthernetCard method
Add net.adapter option to network flag