YARN-530. Defined Service model strictly, implemented AbstractService for robust subclassing and migrated yarn-common services. Contributed by Steve Loughran.
YARN-117. Migrated rest of YARN to the new service model. Contributed by Steve Louhran.
MAPREDUCE-5298. Moved MapReduce services to YARN-530 stricter lifecycle. Contributed by Steve Loughran.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1492718 13f79535-47bb-0310-9956-ffa450edef68
YARN-746. Renamed Service.register() and Service.unregister() to registerServiceListener() & unregisterServiceListener() respectively. Contributed by Steve Loughran.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1492780 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4902. DFSClient#getSnapshotDiffReport should use string path rather than o.a.h.fs.Path. Contributed by Binglin Chang.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1492791 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HDFS-4311-trunk-gd