Allow hooking into logging subsystem through Management API

Provide a way to poll log messages through the management API.

Could be then used in the AS console. Some kind of detached window, or perhaps tab, with log, perhaps pushed through Servlet 3.2's onDataAvailable() ...

Note that this is different from AS7-2213, which needs AS to keep some history. This doesn't.

BTW, JBDS gets the logs through SSH, because the AS may fail booting before anything is able to hook in like this.