Introduce socket factory

We need to be able to produce both SSL and Raw sockets in a configurable fashion. It cannot be either or, as we need an interim path during cluster upgrade where both types of sockets are available and can fall-back from encrypted to non-encrypted communication.

The idea would be to have something like Socket::create(flags). If more than one type is listed, we need to use the 'composable' socket (which is a wrapper object that enables the fallback mechanism)