Problem user permission with policy cache directory

[barbyware]

Dear Sir,

I use your plugin for an older versionspark 2.3 and ranger.

I detect some problem, the first have been solved modified the session.py of pyspark.

The second it is about the cache dir, I use several users and each users generate a cache policy directory. I think that is is posible to change Scala in order to use a /tmp/user policiycache dir, may be easy I think only I need made some changes in the RangerSparkPlugin.scala near val cacheDir = new File(rangerConf.get("ranger.plugin.spark.policy.cache.dir"))

I hope use the submarine project in the near future.

[yaooqinn]

looks reasonable