[WFLY-490] RBAC for standalone servers

First merge of RBAC work to master.

This focuses on securing the central( (i.e. non-JMX) managment API for standalone servers. RBAC in a managed domain will not work with the commits in this PR. There's some configuration stuff related to managed domain here, but it's not actually tied into running services.

RBAC for JMX is not complete in this PR; that will be completed in later PRs.