Remove redeemable code

I don't think this feature it was ever used. It was introduced in commit
49dec6061 as part of a feature that was removed in commits 1cd47da9d and
c45a0bd8ac.

app/controllers/users/registrations_controller.rb

@@ -6,9 +6,7 @@ class Users::RegistrationsController < Devise::RegistrationsController
   invisible_captcha only: [:create], honeypot: :address, scope: :user
 
   def new
-    super do |user|
-      user.use_redeemable_code = true if params[:use_redeemable_code].present?
-    end
+    super
   end
 
   def create
@@ -64,18 +62,13 @@ class Users::RegistrationsController < Devise::RegistrationsController
   private
 
     def sign_up_params
-      if params[:user].present? && params[:user][:redeemable_code].blank?
-        params[:user].delete(:redeemable_code)
-      end
-
       params.require(:user).permit(allowed_params)
     end
 
     def allowed_params
       [
         :username, :email, :password,
-        :password_confirmation, :terms_of_service, :locale,
-        :redeemable_code
+        :password_confirmation, :terms_of_service, :locale
       ]
     end
 

app/models/user.rb

@@ -89,7 +89,7 @@ class User < ApplicationRecord
 
   accepts_nested_attributes_for :organization, update_only: true
 
-  attr_accessor :skip_password_validation, :use_redeemable_code, :login
+  attr_accessor :skip_password_validation, :login
 
   scope :administrators, -> { joins(:administrator) }
   scope :moderators,     -> { joins(:moderator) }

app/views/users/registrations/new.html.erb

@@ -15,7 +15,6 @@
   <div class="row">
     <div class="small-12 column">
 
-      <%= f.hidden_field :use_redeemable_code %>
       <%= f.hidden_field :locale, value: I18n.locale %>
 
       <%= f.text_field :username,  autofocus: true, maxlength: User.username_max_length,
@@ -30,10 +29,6 @@
       <%= f.password_field :password_confirmation, autocomplete: "off",
                                                    label: t("devise_views.users.registrations.new.password_confirmation_label") %>
 
-      <% if resource.use_redeemable_code %>
-        <%= f.text_field :redeemable_code %>
-      <% end %>
-
       <%= f.check_box :terms_of_service,
                       label: t("devise_views.users.registrations.new.terms",
                                terms: new_window_link_to(t("devise_views.users.registrations.new.terms_link"),