title: How to specify the path where saveAsTable saves files to?
body: <p>I am trying to save a DataFrame to S3 in pyspark in Spark1.4 using DataFrameWriter </p>
  
  <pre><code>df = sqlContext.read.format("json").load("s3a://somefile")
  df_writer = pyspark.sql.DataFrameWriter(df)
  df_writer.partitionBy('col1')\
           .saveAsTable('test_table', format='parquet', mode='overwrite')
  </code></pre>
  
  <p>The parquet files went to "/tmp/hive/warehouse/...." which is a local tmp directory on my driver.</p>
  
  <p>I did setup hive.metastore.warehouse.dir in hive-site.xml to a "s3a://...." location, but spark doesn't seem to respect to my hive warehouse setting.</p>