allow dual posix/windows test-kitchen use

[troyready]

A small enhancement would make this awesome plugin even better:

Would it be possible to rebase the init_command monkey patching off the powershell conditional in the upstream test-kitchen gem? As it stands now, the mkdir -p command is being executed on windows platforms even when they aren't using the kitchen-sync transports.

I tested this by just copying over the upstream init_command code and removing the rm -rf part. Would be happy to open a pull request along these lines.

[coderanger]

What we should probably do is check if instance.transport.is_a? for my two classes and if not just delegate to super.

[scopenco]

+1 This problem really annoying, especially when you have suites on linux and windows in one testkitchen env.