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.
Merge pull request #1729 from alphagov/review_created

Publish permission based on submitter rather than creator