HDFS-7199. DFSOutputStream should not silently drop data if DataStreamer crashes with an unchecked exception (rushabhs via cmccabe)
(cherry picked from commit 56257fab1d5a7f66bebd9149c7df0436c0a57adb)
(cherry picked from commit 6f7ce842c015fedb30ec762caeb37a64e8258c4a)
YARN-2767. Added a test case to verify that http static user cannot kill or submit apps in the secure mode. Contributed by Varun Vasudev.

(cherry picked from commit 7a4c92a9d55fcecef066053ac30dff0fcd4ec90c)