Fix two bugs in WinSSH -- a hang when executing powershell via SSH, and when cmd shell is default renaming computer was attempting to execute powershell commands via a batch script

plugins/communicators/winssh/communicator.rb

@@ -36,7 +36,7 @@ module VagrantPlugins
           remote_name = "#{machine_config_ssh.upload_directory}\\#{File.basename(tfile.path)}.#{remote_ext}"
 
           if shell == "powershell"
-            base_cmd = "powershell -File #{remote_name}"
+            base_cmd = "powershell -File #{remote_name} -InputFormat None"
             tfile.puts <<-SCRIPT.force_encoding('ASCII-8BIT')
 Remove-Item #{remote_name}
 Write-Host #{CMD_GARBAGE_MARKER}

plugins/guests/windows/cap/change_host_name.rb

@@ -23,7 +23,8 @@ module VagrantPlugins
           machine.communicate.execute(
             script,
             error_class: Errors::RenameComputerFailed,
-            error_key: :rename_computer_failed)
+            error_key: :rename_computer_failed,
+            shell: "powershell")
 
           machine.guest.capability(:reboot)
         end