Create GooderData::Project that can add users

 - public api_to method in ApiClient to allow non implemented apis to be used
 - public get and post method in ApiClient for api implementation facilities
 - create class GooderData::Project
 - move project related methods from ApiClient to Project
 - add method add_user to GooderData::Project
 - rename successfull_login_options to test_options
 - update README.md