Add OAuth API methods.
Massive request refactoring.
Refactored logic into Clients::request and Clients::boolean_request methods.
Removed 'auth_params' from every request, in addition to updating all requests to match the new format.
Updated gists specs to resolve error for checking against non-existent gist.
Add OAuth specs and doc examples.
Update config.sample.yml and Client::basic_auth_params.