In development, add concurrently to start type-generation alongside app boot

[damassi]

As more code is written / ported to TypeScript, it's important that graphql type-generation is continually running in storybooks (as well as node app) lest things get out of sync as edits to queries are made on the fly.

In Reaction we do it like so (with Relay):

"storybook": "concurrently --raw --kill-others 'yarn relay --watch' 'start-storybook --quiet -s ./public -p 9001'"

In Ervell can be something similar:

"start": "concurrently --raw --kill-others 'yarn generate-types:watch' 'node -r dotenv/config src/index.js'"