YARN-2635. TestRM, TestRMRestart, TestClientToAMTokens should run with both CS and FS. (Wei Yan and kasha via kasha)

(cherry picked from commit 80d11eb68e60f88e16d7d41edecbddfc935a6b10)

Conflicts:
	hadoop-yarn-project/CHANGES.txt
	hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/security/TestClientToAMTokens.java
YARN-2635. Merging to branch-2.6 for hadoop-2.6.0-rc1.

(cherry picked from commit 81dc0ac6dcf2f34ad607da815ea0144f178691a9)

Conflicts:
	hadoop-yarn-project/CHANGES.txt
YARN-2853. Fixed a bug in ResourceManager causing apps to hang when the user kill request races with ApplicationMaster finish. Contributed by Jian He.

(cherry picked from commit 3651fe1b089851b38be351c00a9899817166bf3e)

Conflicts:
	hadoop-yarn-project/CHANGES.txt
YARN-2846. Incorrect persist exit code for running containers in reacquireContainer() that interrupted by NodeManager restart. Contributed by Junping Du

(cherry picked from commit 33ea5ae92b9dd3abace104903d9a94d17dd75af5)
YARN-2853. Merging to branch-2.6 for hadoop-2.6.0-rc1.

(cherry picked from commit d648e60ebab7f1942dba92e9cd2cb62b8d70419b)

Conflicts:
	hadoop-yarn-project/CHANGES.txt
MAPREDUCE-6156. Fetcher - connect() doesn't handle connection refused correctly. Contributed by Junping Du

(cherry picked from commit 177e8090f5809beb3ebcb656cd0affbb3f487de8)
YARN-1964. Adding changelog back in.

(cherry picked from commit 4e9b46da11f79b4ca59c18769925b477ec1bf354)
HDFS-7385. ThreadLocal used in FSEditLog class causes FSImage permission mess up. Contributed by jiangyu.

(cherry picked from commit b0a41de68c5b08f534ca231293de053c0b0cbd5d)
(cherry picked from commit 4e9001530f7bc414b43723858cf7984f707b30e0)
(cherry picked from commit ed2a4db6d4dbb1e0a2d589dda9cdea281e8e5d39)
Preparing to release hadoop-2.6.0-rc1.

(cherry picked from commit 9ff7315cbe9804bebcd1ec093fac7828a72ddf59)

Conflicts:
	hadoop-common-project/hadoop-common/CHANGES.txt
	hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
	hadoop-mapreduce-project/CHANGES.txt
	hadoop-yarn-project/CHANGES.txt

(cherry picked from commit 98a4538cf4b4fd87409fe364487825a4f9df2872)