YARN-2527. Fixed the potential NPE in ApplicationACLsManager and added test cases for it. Contributed by Benoy Antony.

(cherry picked from commit 1c93025a1b370db46e345161dbc15e03f829823f)
YARN-2628. Capacity scheduler with DominantResourceCalculator carries out reservation even though slots are free. Contributed by Varun Vasudev
(cherry picked from commit 054f28552687e9b9859c0126e16a2066e20ead3f)
HADOOP-11151. Automatically refresh auth token and retry on auth failure. Contributed by Arun Suresh.

(cherry picked from commit 2d8e6e2c4a52a4ba815b23d6d1ac21be4df23d9e)