Revert "Implementing an asynchronous client on top of the existing one"

This reverts commit 58eb84e208d79fe690c5e2a0fdfc37e30d167240.
We rather want to implement this functionality as an AsyncHttpRequester
Implementing an asynchronous HttpRequester called AsyncHttpRequester
Merge pull request #3 from mkischel/master

Follow up on implementation of asynchronous requests