Add winrm response to 2.0 branch

Hello,

I have been using this gem in some of our connection libraries for communicating with nodes that are registered in Chef.

I ended up getting a stack trace on a piece of code (linked here)[https://github.com/RiotGames/ridley/blob/master/lib/ridley/host_connector/winrm/command_uploader.rb#L82]. Unfortunately, I am not sure where the communication broke down (NoMethodError [] on NilClass), but I believe that this points to a bigger problem - the response back from the `cmd` or `run_cmd` method is nothing more than an Array.

This pull is an attempt to introduce a new class `WinRM::Response` that holds the important information about a machine's response to a winRM call. I based this pull off of the `working` branch, because I saw that was the branch you have been working on, and a new major version seemed to be the best fit for this kind of change.