[WFLY-245] Add cross-site replication support for EAP

This pull request does the following:
- adds cross-site (xsite) replication support at the JGroups and Infinispan level
- adds XSLT scripts for building xsite server configurations
- adds a 4 node, 3 site server deployment LON(node0, node1), NYC(node2), SFO(node3) which should be suitable for all further xsite testing
- adds in the first of several test cases to check xsite features against the 4 node configuration

This is the bulk of the xsite management implementation; a few smaller additional PRs will follow.