Write path of spark config volume to UPDATE_SPARK_CONF_DIR
Write path of spark config volume to UPDATE_SPARK_CONF_DIR

This change puts the path of the spark config volume in
UPDATE_SPARK_CONF_DIR instead of SPARK_CONF_DIR in spark
cluster pods.  This allows the startup script to check for
presence of the directory and handle it rather than
directly changing where spark looks for it's configuration.

radanalyticsio/oshinko-cli,radanalyticsio/oshinko-cli,crobby/oshinko-cli,tmckayus/oshinko-cli,radanalyticsio/oshinko-cli,crobby/oshinko-cli,tmckayus/oshinko-cli,tmckayus/oshinko-cli,crobby/oshinko-cli