Exclude BusinessSupportEditions with non-live artefacts in results.

It's possible to archive an artefact associlated with a BusinessSupportEdition
making the content go away but still searchable via the API. So filter
results to exclude non-live artefacts.
https://govuk.zendesk.com/agent/#/tickets/821973

Please enter the commit message for your changes. Lines starting
Make results filtering stylish
Merge pull request #203 from alphagov/exclude_bsf_editions_with_archived_artefacts

Exclude BusinessSupportEditions with non-live artefacts in results.