#13 Refactor public API abstractions.
#13 Refactor public API abstractions.

We need to expose completely different abstractions than what we've done so far. But it would be nice not to break currently existing code.

Introducing sockjs.ServerInstance, but sockjs.Server should still work as previously defined.

sockjs/sockjs-node,modulexcite/sockjs-node,modulexcite/sockjs-node,sockjs/sockjs-node