Major touchup

* Added docblocks
* Added namespace
* Improved composer configuration
* Streamlined the API (BC Breaks).
* Refactored code for more readability
* Added adapters. Guzzle as client is now interchangeable.
* Added request and response filters. Users can now modify the Symfony requests and responses to their liking.
I liked it more as well. @omares I would keep the `forward` and `to` methods on the Proxy object. The Factory class can then have a `create` method and a `forward` method as well that calls create internally. Then you can do this:

    Factory::create()->forward(..)->to(..)

Or

    Factory::forward(...)->to(...)