User Story 19, Item Filter by Active Status

[megstang]

As a visitor
When I visit a Merchant Items Index page
Then I see a link to show only active items
And I also see a link to show only inactive items
When I click the link
Then my path is something like '/merchants/:merchant_id/items?active=true'
And I see only the Items sold by the merchant that are active/inactive.

DO THESE STORIES FIRST:

• User Story 7, Item Index

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#108

child of turingschool-examples#130

depends on turingschool-examples#121