shipment controller

[cfanoulis]

The meat of the whole system :)

• PUT /ship - creates a shipment
• GET /shipment/:id - retrieves a shipping mission. id is the airtable ID for said mission
• PATCH /shipment/:id - edits a shipment, BEFORE THE LABEL IS CREATED. If a label is created, we return 400 (needs a better code). id is the airtable ID for said mission
• DELETE /shipment/:id - deletes a shipment BEFORE THE LABEL IS CREATED. If a label is created, we return 400 (needs a better code). id is the airtable ID for said mission.
• GET /shipments/:id/label - Buys & generates labels for the shipment. Returns a 2 page PDF, including the outer address label & the inside note. Accepts a query param method that can override the default shipping method of the scenario