[WFLY-1430] First cut of cluster subsystem.
Port cluster subsystem to new wildfly-clustering-api.
[WFLY-1430] Second cut of cluster subsystem.
[WFLY-1430] Update maven versions.
[WFLY-1430] Update for EJB subsystem refactoring.
[WFLY-1430] Fixups based on PR feedback.
[WFLY-1430] Define org.wildfly.extension.clustering.monitor module.
[WFLY-1430] Fix typo in testcase..
[WFLY-1430] Fixup channel identification, service loader naming and maven version.
[WFLY-1430] Update maven version.