Add margin to beta notice on stats announcements index.
Merge pull request #1614 from alphagov/add_margin_to_stats_announcements_index_beta_notice

Add margin to beta notice on stats announcements index.
Fix for beta notice indentation bug on statistics announcements.
Handle empty pages by 404

* Render a 404 instead of an empty services and info page
* Update gds_api_adapters gem to version 12.4.1 to use Rummager test
  helpers
Sort services and info data by title

Adds search query param to get Rummager response alphabetically sorted by title
Adds styling tweaks to "see more" links