app/models/brand.rb: Add validation.
app/models/product.rb: Add validation.
app/views/products/show.html.erb: Add link to new item form.
Arrange new item page.
Uploading item is abalable.
app/views/items/show.html.erb: Display product name instead of product id.
Arrange item index page.
Arrange item index page for unsigned in users.
app/views/products/show.html.erb: Fix.
.gitignore: Update.
Arrange edit item page.
Hide item that stil not release.
Link from item index page to product page and brand page.