User Story 12, Item Delete

[megstang]

As a visitor
When I visit an item show page
Then I see a link to delete the item
When I click the link
Then a 'DELETE' request is sent to '/items/:id',
the item is deleted,
and I am redirected to the item index page where I no longer see this item

Checklist:

• base tests are written
• base code is written to pass tests
• edge case ("sad path") tests written (if required)
• edge case code written (if required)
• code is tested in development
• code is reviewed
• branch is merged
• all tests still pass

child of turingschool-examples#122

child of turingschool-examples#130