INT-3527: Provide some useful changes

JIRA: https://jira.spring.io/browse/INT-3527

* `WebSocketInboundChannelAdapter` now handles `CONNECT` STOMP message and sends `CONNECT_ACK` message to the `WebSocketSession` immediately
* `ExpressionMessageProducerSupport` implementations now check the result of `expression` and if it is a `Message<?>` it is sent to channel without creating a new one
which has wrapped that `Message<?>` to the `payload` before
* Add `<script>` support to the `<outbound-channel-adapter>`
* Upgrade to the SF 4.1.1
* Add appropriate notes to the Docs
Sorry, not catched it. If you mean `StompCommand.CONNECTED`, then `StompSubProtocolHandler` properly convert this `SimpMessageType.CONNECT_ACK` to the `StompCommand.CONNECTED` and send really this command to the client and, of course, publish it to the application as an event. 
This is just a Server event and message type.
Client can be subscribed to that `StompCommand.CONNECTED` response to do appropriate logic.

If you mean that case when `StompBrokerRelayMessageHandler` sends `StompCommand.CONNECTED`, it won't be our case. Because that operation from Broker is thing-in-itself and it is just sent to the client as is.
Here we handle an `inbound` case: just after WebSocket frame has been converted to the STOMP Message. And it is before Broker interaction. And the more: it is only, when we aren't within Broker.