[WWW-2486] properly include the spec factories
[WWW-2486] make #send_request a private method
[WWW-2486] get these factories working for real
[WWW-2486] specs for #estimate
[WWW-2486] require stuff in little_finger.rb
[WWW-2486] invalid faker addresses cause 500 error for avatax
[WWW-2486] error responses weren't returning correctly
[WWW-2486] more factory stuff
[WWW-2486] test #get
[WWW-2486] fix factory bug
[WWW-2486] split tests up for faster runtime
[WWW-2486] fix spec; fixed discount is spread amongst line items