YARN-1182. MiniYARNCluster creates and inits the RM/NM only on start() (Karthik Kambatla via Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1532113 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10040. Merging change r1532136 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1532138 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5352. Merge change r1532158 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1532159 13f79535-47bb-0310-9956-ffa450edef68