Allow using an SMTP server without authentication (#1597)

* Allow using an SMTP server without authentication (e.g Postfix relay on the same host) by setting SMTP_LOGIN and SMTP_AUTH_METHOD to 'none'

* Add note in .env.production.sample about SMTP settings for servers where no auth is required

* Assume that SMTP_LOGIN and SMTP_PASSWORD will be blank if we set SMTP_AUTH_METHOD to none

config/environments/production.rb

@@ -100,8 +100,10 @@ Rails.application.configure do
     :address              => ENV['SMTP_SERVER'],
     :user_name            => ENV['SMTP_LOGIN'],
     :password             => ENV['SMTP_PASSWORD'],
+
     :domain               => ENV['SMTP_DOMAIN'] || ENV['LOCAL_DOMAIN'],
-    :authentication       => ENV['SMTP_AUTH_METHOD'] || :plain,
+    :authentication       => ENV['SMTP_AUTH_METHOD'] == 'none' ? nil : ENV['SMTP_AUTH_METHOD'] || :plain,
+
     :openssl_verify_mode  => ENV['SMTP_OPENSSL_VERIFY_MODE'],
     :enable_starttls_auto => ENV['SMTP_ENABLE_STARTTLS_AUTO'] || true,
   }