INT-3518: Upgrade versions and some cleanup

JIRA: https://jira.spring.io/browse/INT-3518
INT-3515: Fix Some WebSockets Issues

JIRA: https://jira.spring.io/browse/INT-3515

Change test suite to the Tomcat according IO

INT-3515: IllegalStateException for the `WebSocketInboundChannelAdapter`, when `useBroker = true`, but there is no Broker Relay in the Context
INT-3522: MQTT XSD: Fix client-factory attr type

JIRA: https://jira.spring.io/browse/INT-3522
INT-3511: Document WebSocket Support

JIRA: https://jira.spring.io/browse/INT-3511
The note about Broker destinations
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