Better support for options to WinRM::HTTP::HttpTransport

Hello,

I began experimenting with your excellent gem yesterday but hit a roadblock with the HTTP transport options. I needed to set ":basic_auth_only => true" but was unable to. This patch allows the Cap task to set both winrm_basic_auth_only and winrm_disable_sspi and have their values passed appropriately. I hope you find this patch helpful.

Thank you for your work creating the gem.

Best regards,
Jerry D'Antonio