Add missing options to invisible captcha initializer

These options had been added in the gem's initializer by version 2.0,
but we forgot to add them to our initializer file. So we're doing it
now.

config/initializers/invisible_captcha.rb

@@ -2,6 +2,10 @@ InvisibleCaptcha.setup do |config|
   config.visual_honeypots    = false
   config.spinner_enabled     = false
   config.timestamp_threshold = 4.seconds
+  # config.honeypots           << ['more', 'fake', 'attribute', 'names']
+  # config.timestamp_enabled   = true
+  # config.injectable_styles   = false
+
   # Leave these unset if you want to use I18n (see below)
   # config.error_message           = 'You are a robot!'
   # config.sentence_for_humans     = 'If you are a human, ignore this field'