Chef/ChefClient provisioner fixes, Linux/OS X host OS fixes

My organization had a need to spawn Windows 2008 VMs on Linux and OS X guests and provision them against a Chef server.  I extended vagrant-windows to provide this functionality.  It's not perfect but I'm sure the added functionality will be useful for someone.

The distro-finding dispatch logic should also now work, so if someone wants/needs to add behavior specific to a particular flavor/vintage of Windows, the groundwork is there.

Unfortunately, none of this work is going to be compatible with Vagrant 1.1 (nor, for that matter, is the vagrant-windows gem), so at some point all of this will have to be converted to 1.1's plugin architecture.

(Maybe someone who _really_ wants all this to work in VMware will take it on?)