[#108] "Error: Unencrypted communication not supported" with 0.8.0 and winrm #108

@adamedx  @muktaa 
It includes:
1> I've added changes to fix https://github.com/opscode/knife-windows/issues/108 issue.
2> @siddheshwar-more has fixed bug related to winrm session exit code

http://msdn.microsoft.com/en-us/library/aa384293(v=vs.85).aspx

```
Use Basic authentication. The client presents credentials in the form of a user name and password, directly transmitted in the request message. You can specify only credentials that identify a local administrator account on the remote computer.
```

A comment like this would be more concise:
```
# WinRM Basic Auth only supports authenticating as a local administrator
if username_contains_domain?
  if Chef::Platform.windows?
    ui.info "Switching to Negotiate authentication, Basic does not support domain authentication"
    require 'winrm-s'
    session_opts[:transport] = :sspinegotiate
    session_opts[:disable_sspi] = false
  else
    raise "Only basic authentication is supported from non-Windows clients which only supports authenticating as a local user."
  end
end
```