YARN-1410. Added tests to validate that clients can fail-over to a new RM
after getting an application-ID but before submission and can still submit
to the newly active RM with no issues. Contributed by Xuan Gong.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1575478 13f79535-47bb-0310-9956-ffa450edef68