YARN-1176. RM web services ClusterMetricsInfo total nodes doesn't include unhealthy nodes (Jonathan Eagles via tgraves)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1522069 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-0.23' into branch-0.23-gd
Merge remote branch 'origin/branch-0.23-gd' into fb-HADOOP-9078-branch-0.23-gd