HDFS-6480. Move waitForReady() from FSDirectory to FSNamesystem. Contributed by Haohui Mai.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1603705 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6563. NameNode cannot save fsimage in certain circumstances when snapshots are in use. Contributed by Aaron T. Myers.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1603712 13f79535-47bb-0310-9956-ffa450edef68