Major refactoring, new features version 3.0.0

[sealedtx]

Just pushed to a new branch refactored version of this library which includes:

• better project stucture and class naming;
• request/reponse pattern;
• async parsing api;
• proxy support**;
• retries on failure**;

** not well tested yet

This version is still in development, so comments and suggestions are welcomed.