Added dependencies faraday with faraday_middleware.
Added development dependency mocha.
Created an issuer class which can contain one issuer.
Created an issuers class which can retrieve a list of issuers.
Created a cardgate_connection test helper method which can be used to stub faraday connections.
Added fixtures for cardgate responses.
Added a connection method to Gateway which can be used to send authenticated requests to the cardgate API.
Added an ideal module to require files.
Added custom cardgate exception.