Add a skeleton of a Rails API app

- Generated with `rails-api new courts-api --skip-sprockets --skip-javascript --skip-test-unit --skip-spring` as per the HMRC Manuals API.
first commit of api spec
changes following Jamie's comments

- UUID syntax
- URL format
- some wording
- restrictions on text data passed
- slug rules for receiver
link to API spec
don't assume 'courts' is in the URLs. Also, receiver can send 200 or 201.
add court paylod and court list examples, resolve some issues
creation date not needed, as admin-db specific
more details removed and marked TBD
removed. Will be specified later
Merge pull request #1 from maxf/master

first commit of api spec
Tweak the title and description of the app
Remove SQLite from the Gemfile and all references to a database

- If we have a database, it won't be SQLite.
- Remove Spring as it doesn't offer us anything.
- Pin the rails-api version.
Don't specify a Ruby version in bin/* files
Remove .keep files for assets, models and concerns
Remove ActionMailer and ActiveRecord
We don't need locale files or route examples
Keep public/ for potential future use, but remove its contents
Merge pull request #2 from alphagov/add_initial_rails-api_app

Add a skeleton of a Rails API app
Merge pull request #3 from alphagov/tweak_readme

Tweak the title and description of the app
Pin the rails-api version in the Gemfile.lock

- This should have been in #2, 68d05ad39185e9dd812480a72bcdd16d57caaf2a.