allows modifying properties in vm.tools

Generic command for modifying properties in vm.config.tools

PLUS:
You can disable VMware Image Customization after every power cycle with

```knife vsphere vm toolsconfig myvirtualmachine pendingCustomization -e```

See:
https://communities.vmware.com/thread/286939
and
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2078352