YARN-2795. Fixed ResourceManager to not crash loading node-label data from HDFS in secure mode. Contributed by Wangda Tan.

(cherry picked from commit ec6cbece8e7772868ce8ad996135d3136bd32245)
HDFS-7147. Update archival storage user documentation. Contributed by Tsz Wo Nicholas Sze.
YARN-1922. Fixed NodeManager to kill process-trees correctly in the presence of races between the launch and the stop-container call and when root processes crash. Contributed by Billie Rinaldi.

(cherry picked from commit c5a46d4c8ca236ff641a309f256bbbdf4dd56db5)