HADOOP-9173. Add security token protobuf definition to common and use it in hdfs. Contributed by Suresh Srinivas.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1428970 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9173. Add security token protobuf definition to common and use it in hdfs. Contributed by Suresh Srinivas.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1428972 13f79535-47bb-0310-9956-ffa450edef68