Move common derived service spec_helper setup into restpack_service

[GavinJoyce]

From https://github.com/RestPack/restpack_core_service/blob/master/spec/spec_helper.rb

Most (all?) of this can be extracted to https://github.com/RestPack/restpack_service/blob/master/lib/restpack_service/support/spec_helper.rb

config = YAML.load_file('./config/database.yml')
ActiveRecord::Base.establish_connection(ENV['DATABASE_URL'] || config['test'])

migrations_path = File.dirname(__FILE__) + "/../db/migratore"
migrator = ActiveRecord::Migrator.new(:up, migrations_path)
migrator.migrate

FactoryGirl.find_definitions

DatabaseCleaner.strategy = :transaction

RSpec.configure do |config|
  config.include FactoryGirl::Syntax::Methods

  config.before(:each) do
    DatabaseCleaner.start
  end

  config.after(:each) do
    DatabaseCleaner.clean
  end
end