INT-3418: Prepare 4.1 VERSION

JIRA: https://jira.spring.io/browse/INT-3418

* Create 4.1 XSD
* Clean up Docs for 4.1
* Prepare WebSocket module
* Add Reactor dependency
* Remove Eclipse and SNV artifacts

Phase #1: prepare
Phase #2: xsd-1.0 -> 4.1
Phase #2: xsd-2.0 -> 4.1
Phase #3: xsd-2.1 -> 4.1
Phase #4: xsd-2.2 -> 4.1
INT-3418: Phase #4: xsd-2.2 -> 4.1
INT-3418: Phase #6: xsd-4.0 -> 4.1
INT-3418: Final Phase: Cleanup