Implement acouchbase for Windows

Unfortunately acouchbase appears not to have been targeted to Windows ProactorEventLoop, which is now the default for Python>=3.8, and relies on methods in the event loop (add_reader and remove_reader) that are not present on the default Windows event loop (ProactorEventLoop) leading to NotImplementedErrors being raised. A quick fix would be to mandate the use of SelectorEventLoop, at least until a Proactor-compatible solution can be arrived at - see https://github.com/jupyter/notebook/issues/5097 for reference.