add published at to dsu schema
Add schema for MAIB report doctype

This commit contains the required schema for indexing reports by the
Marine Accident Investigation Branch in Rummager when published by
Specialist Publisher.
Merge pull request #302 from alphagov/add-schema-for-maib-reports

Add schema for MAIB report doctype
Rename published_date to first_published_at
Merge pull request #301 from alphagov/feature/add-published-at-to-dsu

Add published at to dsu schema
Remove gemfury
Merge pull request #304 from alphagov/remove-fury

Remove gemfury
Add RAIB Report doctype schema

This commit adds the doctype schema for Rail Accident Investigation
Branch reports as published by Specialist Publisher.
Merge pull request #303 from alphagov/raib-reports

Add RAIB Report doctype schema
Singularise MAIB and RAIB report types

An indidividual report can't be a safety bulletins.
Merge pull request #305 from alphagov/singularise-maib-and-raib-report-types

Singularise MAIB and RAIB report types