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.
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.
Add a .ruby_version which is 2.1.4, the latest we have in Puppet
Add the logstasher gem
Add RSpec as our test framework
Add a healthcheck route that responds with "OK", and a test for it

- We're not letting Rails assign default .xml/.json extensions to
  the routes because we're only going to return JSON, not XML or HTML.
Add jenkins.sh and jenkins_branches.sh for CI builds
Add the unicorn gem
Remove secrets.yml as per the initial setup of the hmrc-manuals-api

- The initial setup of the HMRC Manuals API cited this removal as "not
  needed because the API will not be doing cookie signing." See
  https://github.com/alphagov/hmrc-manuals-api/commit/477d6500b7511a88e49615fbb48c01f48b59d754.
  It can be added back in later if it does turn out we need it here, as
  it was over in HMRC Manuals API land.