app/views/items/{edit,new}.html.erb: Display Hold instead on hold.
app/views/products/show.html.erb: Fix typo.
Generate migration to add copyright to products table.
db/schema.rb: Migrate.
Display copyright at product page.
Display copyright at item page.
app/views/layouts/application.html.erb: Add comment for copyright.
Generate migration to add r18 to products table.
db/schema.rb: Migrate.
Display message for adult on product/item page.
app/views/products/show_not_owner.html.erb: Do not display descrition and note.
Fix typo 'Md5' -> 'MD5'.
Generate check_items controller.
config/routes.rb: Route to check_items page.
Add page to check item.