ISPN-3935 True Async remote clients (HotRod, etc) API

https://issues.jboss.org/browse/ISPN-3935

DO NOT INTEGRATE YET
LockingTest is still failing, although I can't find out why - at one moment, a request is flushed (and I can see from tcpdump that it went over network) but it is not received at the server. Mysterious - I'd like to reconfirm that.
That's also why I left some debug logs scattered around.

This brings truly asynchronous API to the HotRod client - asynchronous request does not occupy a thread from async thread pool, only a socket (in the future multiple requests could share the socket as well, using it exclusively only for a short time). Java 7 NIO.2 (also called AIO) is required.
Includes also async SSL support (that was tricky!)