-amends the routes for invoice_items
-creates directory app/controllers/api/v1/invoice_items that has the finders_controller, invoice_controller, and item_controller
-spec harness passes
-adds tests for invoice_items record endpoints (for record endpoints it doesn't test for find by created_at/updated_at; I could not get the test to work for those and didn't want to waste anymore time, they pass on the spec harness though) and relationship endpoints
-amends the routes for invoice_items -creates directory app/controllers/api/v1/invoice_items that has the finders_controller, invoice_controller, and item_controller -spec harness passes -adds tests for invoice_items record endpoints (for record endpoints it doesn't test for find by created_at/updated_at; I could not get the test to work for those and didn't want to waste anymore time, they pass on the spec harness though) and relationship endpoints