Convert data store to Airtable API

[martingaston]

• [x] plan database schema
• [x] set up Airtable database with basic data
• [x] test basic Airtable API request
• [x] add database call to History.js
• [x] add database call to HistoryStationCases.js
• [x] add database call to HistoryCaseRevision.js

[martingaston]

API Reference

/api/history

{ payload: [str1, str2] }

/api/history/:station/

{ payload: [str1, str2] }

/api/history/:station/case/:id

{payload: { title: str, details: str, mark-scheme: [str1, str2] }}