HDFS-6938. Cleanup javac warnings in FSNamesystem. Contributed by Charles Lamb.
Fix CHANGES.txt to keep it consistent with trunk.
HADOOP-7984. Add hadoop --loglevel option to change log level. Contributed by Aikira AJISAKA.
HADOOP-11291. Log the cause of SASL connection failures. Contributed by Stephen Chu.

(cherry picked from commit 7dae5b5a880205fd0125c143c44498db79c19392)