Jetty impl & java client

Did the following changes:

1) Wrote a jetty implementation. It has a few issues at high load.
2) Wrote a java non blocking client for the following reasons:
      -- Clojure client had some issues with servers returning error responses or taking time to return.
      -- Clojure client is blocking so need multiple concurrent client to simulate high client connections.
      -- I don't know clojure & I wanted to make some changes to the client :)
3) Rewrote netty implementation to be completely async (yes, the earlier one was blocking at some point)

I still need to update the documentation.