Add the API to create batch statements, and handle them in CqlRequestHandler.
Investigate if we can get an UNPREPARED response for a bound statement that is part of a batch statement (see TODO in CqlRequestHandler), and how to handle it appropriately. This might be an unsolved issue in 3.x as well.
Batch statements: there's an UNPREPARED response for the first statement to re-prepare in the batch. This is why the code relies on the id in the response and not the initial statement (which is the batch in this case). This repeats as long as there are still statements to prepare.
3.x handles this correctly.