Initialize ssl_bundle_path to nil (just trying to get the gem to work)
Update the person APIResource to use the irregular plural of person
Pipedriver.api_error's first param should be a string, not an object
The first param of Pipedriver.invalid_request_error should be a string
Pass api_token through the querystring for all requests. I'm not sure if this is meant to be how the API works, but I cannot get a POST request to success unless the api_token is on the URL (instead of the payload).