Create class Request
Add constants for methods
Add fields to the class Request
Add a constructor for a class Request
Add methods to control arguments

 - Add method addArg
 - Add method clearArg
Add methods to create a URL

 - Add method createURL
 - Add method signedRequest
 - Add method unsignedRequest
Add signals and slots for requests

 - Add signal requestFinished
 - Add slot sendRequest
 - Add slot responseReceived