[WFLY-958] Messaging: enforce security for in-vm connections

* add override-in-vm-security attribute to hornetq-server.
  Default value is true to keep the same behavior (ie in-vm connections
  overrides the security credentials). Setting it to false means that
  messaging code using in-vm connections *must* have valid user
  credentials (i.e. JMS createSession() without user/password will
  fail).
* bump messaging extension management version to 3.0.0
* bump messaging XML namespace to urn:jboss:domain:messaging:3.0
* add transformation test for messaging 3.0 XML
* add messaging-2.0.0.dmr to subsystem-test framework

JIRA: https://issues.jboss.org/browse/WFLY-958
increase surefire PermGen size to 256MiB
Merge pull request #6259 from jmesnil/WFLY-958_enforce_security_invm_connections

[WFLY-958] Messaging: enforce security for in-vm connections