HDFS-5455. NN should update storageMap on first heartbeat.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-2832@1538787 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5457. Fix TestDatanodeRegistration, TestFsck and TestAddBlockRetry. (Contributed by szetszwo)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-2832@1538794 13f79535-47bb-0310-9956-ffa450edef68