Make abstract requests from Request class

Make requests from Request class to accommodate async requests

Bug fixes for async requests

handle errors when processing async request responses with array_walk and creating model

Accept $params on all methods that make requests

Allow passing custom query parameters for, eg, making async requests

Configurable authorization link

v0.2.1

Enable configuration of getAuthorizationLink

Add delete method to connection

v0.2

add getAuthUrl method to connection