YARN-1915. Fixed a race condition that client could use the ClientToAMToken to contact with AM before AM actually receives the ClientToAMTokenMasterKey. Contributed by Jason Lowe
(cherry picked from commit 5864dd99a419b8a0fb973a4984c0f1d1e02ccf16)
YARN-2314. Disable ContainerManagementProtocolProxy cache by default to prevent creating thousands of threads in a large cluster. Contributed by Jason Lowe
(cherry picked from commit f44cf99599119b5e989be724eeab447b2dc4fe53)