Add AAIB Reports schema

In order to expose AAIB reports in search, we've added the schema for the facets on the reports.

Trello ticket:
https://trello.com/c/X4vUOJzE/203-add-aaib-reports-into-search-results-2
It's fine to change it later; you'll just need to do a deploy:migrations to get the updated configuration.  You shouldn't need to republish documents.