YARN-2865. Fixed RM to always create a new RMContext when transtions from StandBy to Active. Contributed by Rohith Sharmaks
YARN-2802. ClusterMetrics to include AM launch and register delays. (Zhihai Xu via kasha)
YARN-2315. FairScheduler: Set current capacity in addition to capacity. (Zhihai Xu via kasha)