Application blacklist to drop misbehave AM requests

Sometimes there might be some malicious or mis-behave AMs that keep sending invalid resource requests to RM, this causes resource wastes. If such application provides online services, we cannot simply KILL them. Instead it will be extremely useful if RM can black list such applications, drop their requests. So admin could have time to check and then decide how to process. Propose to add an admin command to blacklist applications.

Open this JIRA for discussion, will upload a design doc shortly.