Add initial documentation

With @kalleth and @themitchell
Add case sensitive help text to search form
Merge pull request #287 from alphagov/add-case-sensitive-help-text

Add case sensitive help text to search form
Fix registrations on AAIB reports

The import script added both registration (an array) and registration
string (as string) to extra fields. Desired behaviour was to just use
string.
Removed registration array, and renamed registration string to
registration.
Formatting fix on Dependencies on README

I'm not sure this is the best way of contributing this fix, so feel free to force push this commit out if I did it wrong.
Merge pull request #288 from alphagov/fix-registration-fields

Fix registrations on AAIB reports
Remove `IdGenerator` class and object-constant-based calls of it

The `IdGenerator` object did very little. It can be summed up as the
following bit of code: `SecureRandom.uuid`. Keeping it around doesn't
add anything and it makes it hard to understand why the constant form
of the object is being called in the way it does.

Removing it means there's one less thing to understand in terms of
using the already existing `*Builder` classes.
Merge pull request #285 from alphagov/add-readme

Add initial documentation
Merge pull request #290 from alphagov/reduce-repetition-of-id-generator-calls

Remove `IdGenerator` class and object-constant-based calls of it
Add how to add a new document format to readme

This commit adds a step by step guide for adding a new document format
along with how to to test that document format.
Merge pull request #292 from alphagov/how-to-add-a-new-document-format

Add how to add a new document format to readme
Add MAIB Reports to routes.rb
Add schema for MAIB Reports

Facets for MAIB Reports are vessel type, report type and date of
occurrence.
Add model for MAIB Report

This commit also adds the builder, factory and validator.
Add services for MAIB Reports

Also adds services for the MAIB Report Attachments.
Define repository for MAIB Reports
Add observers for MAIB Reports

This also adds the formatters for the artefact and for indexing by
Rummager along with all the necessary calls for these.
Adding views for MAIB Reports
Add permission check for MAIB Editors + nav link
Add spec for MAIB Report model