Improve error handling (in TwitterErrorHandler)

[lbeuster]

The exception (e.g. on bad request 400) that is thrown by the error handler (delegated call to DefaultResponseErrorHandler.handleError()) doesn't contain the response body anymore since the stream has already been consumed by handleClientErrors() before.
I guess that is the reason why there is a strange System.out.println() with the response body, so it's not completely lost.

It would be nice if the System.out could be removed and the thrown exception could contain the response entity.

For testing I used a search request without a query -> "400 :: Query parameters are missing."