Sync metadata

www.agileplannerapp.com/boards/173808/cards/5444

Publisher has an "Edit in Panopticon" link which
allows section, slug and department to be edited
for an edition. Once artefact was edited in
Panopticon these changes were not be synced
back to the Edition.

commit https://github.com/alphagov/govuk_content_models/commit/58c07c51f9a484fd3adf3ef22536fc3be2f490ae is to make the build green by using
a compatible govspeak version. see https://github.com/alphagov/govspeak/pull/34