Updated interface for authentication so that CS_REST_Wrapper_Base() now accepts an  array, which is used to hold either OAuth details or API key details.
Made CS_REST_TestClients abstract, and added two subclasses for testing using both OAuth and an API key.
In PHP 5 (which CI on runs on) the following idiom is deprecated:  =& new MyObject();
Migrated all tests to use new authentication method.
Fixed bug with basic auth when getting a user's API key. Modified general samples to use OAuth as the authentication method.
Template examples use OAuth to authenticate.
Subscriber examples use OAuth to authenticate.
Segment examples use OAuth to authenticate.
List examples use OAuth to authenticate.
Client examples use OAuth to authenticate.
Campaign examples use OAuth to authenticate.
Updated all existing samples to use OAuth by default.
URI scheme should always be https be default.
Added samples for authenticating using OAuth and an API key.
Added CS_REST_General::authorize_url() plus tests.
Added CS_REST_General::exchange_token() to enable token exchange.
Added samples for CS_REST_General::authorize_url() and CS_REST_General::exchange_token().
README code fixes.
Link to gist which implements OAuth using createsend-php and the Slim framework.
Added the ability to refresh an access token.