Implemented redirect using Observable APIs. Added JUnit tests. Retrofit serialization framework to RestClient.

- Added ribbon-rxnetty module for asynchronous HTTP communication based on Netty and RxJava
- IClientConfig and IClientConfigKey supports typed property
- Updates to serialization factory and serializer interfaces (replaced Guava TypeToken with TypeDef in the interfaces)
- Updates to HttpRequest and HttpResponse interfaces with addition of HttpHeaders

Support for async communication using Apache's HttpAsyncClient. Added streaming interface. Added support for Observable.