Remove video fields from non-video formats

* Video url and summary fields aren’t used, they just clutter the
edition form
* There are only 10 published videos, all in the video format
Remove video icons from table list

* Only video formats will have videos, and that’s guessable from the
format type alone
Use input helper classes for video fields

* Avoid using grid wrappers, the admin gem provides helpers for setting
the maximum width of form elements
Use input helper classes on common attributes

* Avoid using divs as grid wrappers to restrict width of form elements.
The admin gem provides classes for this.
* Remove beta help text, the explanation is extraneous now the feature
has been introduced and understood
Use input helper classes on business support form

* Constrain widths using classes rather than grid wrappers
Whitespace: alignment of tags in business support
Use input helper classes on campaign form
Use input helper classes on answer form
Use input helpers on remaining forms

* Tidy up whitespace for input attributes
* Use more rows for introductory paragraphs (2 isn’t enough for most
content, scrolling the small boxes is painful)
Merge pull request #282 from alphagov/hide-video-fields

Only show video fields on video formats
Merge pull request #283 from alphagov/input-class-helpers

Replace grid wrappers with input helper classes
Move action logic into a new action helper

* Cleanup the view and move logic to a helper
Add auto link gem

* https://github.com/tenderlove/rails_autolink
Make links clickable in notes

* Only link URLs not emails
* Don’t sanitize the output so as to be consistent with simple_format
options
Merge pull request #286 from alphagov/links-in-notes

Make links clickable in notes
Rake task for updating a mainstream slug

Provides a rake task for updating a mainstream slug
by updating all editions, updating the artefact and
reregistering with panopticon.

See:
https://github.com/alphagov/wiki/wiki/Changing-GOV.UK-URLs#making-the-change
Merge pull request #285 from alphagov/feature/rake-task-for-changing-mainstream-slugs

Rake task for updating a mainstream slug
Add STDOUT logging to slug changes

In order to give some feedback add some logging to STDOUT so we know whats happening
Merge pull request #288 from alphagov/feature/add-logging-to-slug-changes-task

Add STDOUT logging to slug changes
Re-write tests to use test helpers for workflow

govuk_content_models introduced test helpers in 24.0.0
which provide a consistent way to test workflow behavior.

also re-opened the BaseProgressor class instead of the
User class, to send notifications after actions are
performed, as that behavior has been delegated-out from
the User to ActionProcessors.