AMBARI-17761. Need to specify HADOOP_CONF_DIR in livy-env (Jeff Zhang via smohanty)

ambari-server/src/main/resources/stacks/HDP/2.5/services/SPARK/configuration/livy-env.xml

@@ -75,10 +75,12 @@
             #!/usr/bin/env bash
 
             # - SPARK_HOME      Spark which you would like to use in livy
+            # - HADOOP_CONF_DIR Directory containing the Hadoop / YARN configuration to use.
             # - LIVY_LOG_DIR    Where log files are stored.  (Default: ${LIVY_HOME}/logs)
             # - LIVY_PID_DIR    Where the pid file is stored. (Default: /tmp)
             # - LIVY_SERVER_JAVA_OPTS  Java Opts for running livy server (You can set jvm related setting here, like jvm memory/gc algorithm and etc.)
         export SPARK_HOME=/usr/hdp/current/spark-client
+        export HADOOP_CONF_DIR=/etc/hadoop/conf
         export LIVY_LOG_DIR={{livy_log_dir}}
         export LIVY_PID_DIR={{livy_pid_dir}}
         export LIVY_SERVER_JAVA_OPTS="-Xmx2g"