Make all formats use @document_fields

Instead of using a custom name for the variable holding
the field values for a document, use @document_fields.
This is more reusable accross the board and allows us
to use more common steps which are much more
maintainable.
Remove duplicate publishing scenarios

These already exist as duplicates in the corresponding publishing
features.
Stop collisions for manual steps

We want to use these for generic document steps. Lets
move these out of the way first so we dont get step
name collisions.
Make edit_[:document_type] method more generic

Editing a document is requires nothing different for each document format. It simply fills in fields, saves and publishes them. By moving the step to go to a particular page we can make this method much simpler. This will allow us to have more generic methods accross the board removing a massive amount of duplication and making the cucumber steps much easier to work with.
Allow CmaCases to be edited with change notes

As with Manuals CmaCases can now be edited with change notes.
Currently these change notes will only be stored against the
SpecialistDocumentEdition and do not create a PublicationLog entry.
 Which currently means change notes will not be able to be used on
the frontend yet. This would require some work in order to make the
PublicationLog work with other formats other than manuals.
Allow DrugSafetyUpdates to be edited with change notes

As with CmaCases allow change notes which are not yet pushed to the PublicationLog
Allow MAIB reports to be edited with change notes

As with CmaCases allow change notes which are not yet pushed to the PublicationLog
MedicalSafetyAlerts can be edited with change notes

As with CmaCases allow change notes which are not yet pushed to the PublicationLog
RAIB Reports can be saved with change notes
Make AAIB Reports use change notes
Add change notes to International Development Funds
Merge pull request #327 from alphagov/feature/major-updates-change-notes

Major updates & change notes