Add rspec filter :silence_stdout

This filter allows redirecting $stdout to prevent too much noise in
specs.

spec/spec_helper.rb

@@ -403,6 +403,15 @@ RSpec.configure do |config|
     end
   end
 
+  # Allows stdout to be redirected to reduce noise
+  config.before(:each, :silence_stdout) do
+    $stdout = StringIO.new
+  end
+
+  config.after(:each, :silence_stdout) do
+    $stdout = STDOUT
+  end
+
   config.disable_monkey_patching!
 end