Add SSL support (issue #106).

We pass lastContext to ConnectionObservable, so all writes will go through whole pipeline.
fireUserEventTriggered belongs to the ChannelInboundHandler interface, so we have to start from the head of the pipeline. With the previous code, we pointed to ObservableAdapter context (the last one in pipeline), and fireUserEventTriggered which was sent to next handler in chain (tail) had no effects.