Add draft functionality to `/tags.json` endpoint.
Add draft functionality to `/tags/:type/:id.json` endpoint.
Add draft functionality to `/with_tag.json` endpoint.
Add draft functionality on `/:artefact_id.json` endpoint.
Merge pull request #194 from alphagov/draft-tags

Add draft tag functionality to tag endpoints.
Bump gds-sso to 9.3.0

This is to fix an issue with transfer ot bearer tokens.  See
https://github.com/alphagov/signonotron2/pull/245 for details.
Merge pull request #195 from alphagov/bump_gds-sso

Bump gds-sso to 9.3.0
Rename creds constant for clarity

Make it clear that the contained token is for asset-manager only, not
for any api clients.
Merge pull request #196 from alphagov/rename_creds_constant

Rename creds constant for clarity
Add state to presented tag.
Merge pull request #197 from alphagov/add-state-to-presented-tag

Add state to presented tag.
Bump content models to 16.1.0

This includes the change to add a workflow for tags, and to make all
new tags draft by default.
Update tests to use the live_tag factory

As the recent changes to the Tag model mean that tags are now created in
draft by default, we need to explicitly create tags in the live state.

This updates all the existing factories in Content API for tags to use
the new 'live_tag' factory. Existing tags which had been manually
created in the draft state have been changed to use the 'draft_tag'
factory.
Merge pull request #198 from alphagov/workflow-for-tags

Bump govuk_content_models to 16.1.0
Bump content models to 16.1.1 for tag draft parent fix.
Merge pull request #199 from alphagov/fix-draft-parent-tags

Bump content models to 16.1.1 for tag draft parent fix.
All Specialist Documents now have a published_at field.

Bump content models to 16.2.0 s.t. the published_at attribute exists.