Added OATH, cleaned up curl for GET/POST, and more

Hello,

Great library it was just missing a few things for my requirements.  I've added OATH support and cleaned up the curl interface for both get/post calls so it can be easily expanded for adding more stub GET methods and new stub POST methods.

Updated the readme as well to include new information and quick start guide using OATH.  I also want to add more functionality down the road but this is where I'm at now.  Welcome more testing and improvements.

Would like to add member variables and beef up the object as well but don't have time right now.