FEATURE: make show_subcategory_list a per-category setting

db/migrate/20170221204204_add_show_subcategory_list_to_categories.rb

@@ -0,0 +1,14 @@
+class AddShowSubcategoryListToCategories < ActiveRecord::Migration
+  def up
+    add_column :categories, :show_subcategory_list, :boolean, default: false
+
+    result = execute("select count(1) from site_settings where name = 'show_subcategory_list' and value = 't'")
+    if result[0] and result[0]["count"].to_i > 0
+      execute "UPDATE categories SET show_subcategory_list = true WHERE parent_category_id IS NULL"
+    end
+  end
+
+  def down
+    remove_column :categories, :show_subcategory_list
+  end
+end