Use -NoProfile in powershell to (hopefully) suppress output

Author: ianfixes

appveyor.yml

@@ -17,6 +17,8 @@ before_test:
   - g++ -v
 
 test_script:
+  # https://help.appveyor.com/discussions/problems/5170-progresspreference-not-works-always-shown-preparing-modules-for-first-use-in-stderr
+  - ps: $ProgressPreference = "SilentlyContinue"
   - bundle exec rubocop --version
   - bundle exec rubocop -D .
   - bundle exec rspec

lib/arduino_ci/arduino_downloader_windows.rb

@@ -10,8 +10,8 @@ module ArduinoCI
   class ArduinoDownloaderWindows < ArduinoDownloader
 
     def powershell(*args)
-      encoded_cmd = Base64.strict_encode64((args.shelljoin + " | Out-Null").encode('utf-16le'))
-      system("powershell.exe", "-encodedCommand", encoded_cmd)
+      encoded_cmd = Base64.strict_encode64(args.shelljoin.encode('utf-16le'))
+      system("powershell.exe", "-NoProfile", "-encodedCommand", encoded_cmd)
     end
 
     def cygwin(*args)