YARN-1611. Introduced the concept of a configuration provider which can be used by ResourceManager to read configuration locally or from remote systems so as to help RM failover. Contributed by Xuan Gong.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1564002 13f79535-47bb-0310-9956-ffa450edef68