Publish permission based on submitter not creator.

When reviewing (2i) an edition, the user should be prevented from publishing
only if they were the one who submitted for 2i, rather than if they were the
original creator.
Create Version in submitted factory.
Fix tests that depend on publishing workflow.

We now check publishing user is not the same as submitting, not creating, user.
Feature tests for publish workflow.
Remove commented code and unused method.
Move submitted_by logic to method on Edition.
Authority tests only stub committed_by method.
Restore code lost in merge.
Editions are sent to publishing API

Whitehall needs to notify the publishing API about published editions, so
that the notifications go on to the publishing message bus.

Editions are registered in the publishing API with a format of "placeholder".
Update Plek to use Plek.find insted of Plek.new.find or Plek.current
Adds PublishingApiTestHelpers

Changes tests to use publishing api test helpers
Add change_note and browse_page keys to attributes_for_publishing_api
Fixes failing unit test

* Force publishing now needs to take into account the PublishingApi
listener: test was updated to use the publishing API helpers

* Remove TimeCop since time is already frozen
Stub publishing API in features
Modify CSS classes on past foreign secretaries page to ensure correct alignment
The alignment got broken when Philip Hammond was added as new foreign secretary
without taking care of the "clear-person" class on the items below.
Merge pull request #1742 from alphagov/past-foreign-secretaries-presentation

Modify CSS classes on past foreign secretaries page to ensure correct al...
Merge pull request #1729 from alphagov/review_created

Publish permission based on submitter rather than creator
Merge pull request #1734 from alphagov/sending-editions-to-publishing-api

Sending editions to publishing api
Show the change type on admin/editions#show

This makes it easier to find to see the type of update on any given
edition.
Merge pull request #1743 from alphagov/change-type

Show the change type on admin/editions#show