In item page, 'Links' is <h3> taged.
app/models/item.rb: Define Item.search for searching items.
app/views/layouts/application.html.erb: Add search form.
app/controllers/items_controller.rb: Fix indents.
app/controllers/items_controller.rb: Support searching items.
In item index page, Display table header 'Item' instead of 'Name'.
app/views/items/show_not_signed_in.html.erb: Indent block.
In item index page, put color links to item page.
In item page, put color to download links.
app/views/products/show_not_owner.html.erb: Indent blocks.
app/views/products/show_not_owner.html.erb: put color to links to item page.
Merge branch 'support-search'