Publish manuals to the Publishing API

The Publishing API will eventually replace the Content API.
Publish manual sections to the Publishing API
Publish manual change notes to the Publishing API

Change notes are added to the 'details' attribute on the 'manual'
content item, rather than being a separate content item.
Send manuals organisation info to Publishing API

The Publishing API has no concept of tagging just yet, so the organisation
association is stored in the 'details' attributes.
Access manual/section attributes using fetch

This means that if the attribute is missing, an exception is thrown
(rather a null being sent to the Publishing API).
Use production Organisations API except in test

In dev, we don't want to incur the cost of depending on Whitehall just for the organisations API.
In test, the organisations API stubs assume that the basepath is `Plek.current.find("whitehall-admin")`.
In preview, the client would have to handle simple auth so pointing to production is simpler.
Calculate manual update type from section update types

A manual update is major if there are any major section updates.
Merge pull request #222 from alphagov/push_manuals_to_content_store

Publish manuals, sections and change notes to the Publishing API