Support re-authentication during the shell

After 8 hours, the server requests re-authentication, so need to support that.

lib/net/winrm/connection.rb

@@ -207,9 +207,9 @@ module Net
 
           def ntlm_transform_response(ntlm_client, response)
             # OMI server doesn't always respond to encrypted messages with encrypted responses over SSL
-            return nil unless response
-            return response.body if response.headers['Content-Type'].first =~ %r{\Aapplication\/soap\+xml}i
-            return '' if response.body.empty?
+            return unless response
+            return if response.headers['Content-Type'] and response.headers['Content-Type'].first =~ %r{\Aapplication\/soap\+xml}i
+            return if response.body.empty?
 
             str = response.body.force_encoding('BINARY')
             str.sub!(%r{^.*Content-Type: application\/octet-stream\r\n(.*)--Encrypted.*$}m, '\1')

lib/rex/proto/http/client.rb

@@ -513,6 +513,7 @@ class Client
 
       ntlm_message_3 = ntlm_client.init_context(ntlm_challenge, channel_binding)
 
+      self.ntlm_client = ntlm_client
       # Send the response
       opts['headers']['Authorization'] = "#{provider}#{ntlm_message_3.encode64}"
       r = request_cgi(opts)
@@ -521,7 +522,6 @@ class Client
       unless resp.kind_of? Rex::Proto::Http::Response
         return nil
       end
-      self.ntlm_client = ntlm_client
       return resp
 
     rescue ::Errno::EPIPE, ::Timeout::Error