Add schema and metadata for MAIB Reports

This commit adds MAIB report facet schema and metadata hash.
It also adds maib-reports to the Panopticon test.
Ticket:
https://trello.com/c/dp6yU20f/369-maib-finder-add-support-to-rummager-and-finder-api-for-maib-reports-1
Merge pull request #69 from alphagov/add-maib-reports

Add schema and metadata for MAIB Reports