Merge pull request #1 from airseed/aa-auth-tests

Adding auth + minor refactor + vcr tests
renamed RestAPI => UserAPI, take id as an param, though optional, when provided access token (which is also optional in 2 cases, we'll be cleaning that later)
fix for bug which caused client_id=[client_id, client_secret, callback_url]
putting in integration tests using config.yml, updated readme with code snippets