title: change path for spark dataframe partition writing
body: <p>I am writing dataframe with partitionBy(part_column) which writes it in output directory with partitions as output_dir/part_column_name=part_value.</p>
  
  <p>Is it any way possible to write in format of output_dir/part_value ?</p>
  
  <p>Current code looks as below</p>
  
  <pre><code>dataframe.write.mode(SaveMode.Overwrite).format("parquet").partitionBy(part_column).save(outputPath)
  </code></pre>
  
  <p>Suppose my partition column is dt. dt has values '20180701','20180702'.
  If I execute</p>
  
  <pre><code>dataframe.write.mode(SaveMode.Overwrite).format("parquet").partitionBy("dt").save("/etl/output").
  </code></pre>
  
  <p>It will create output directories as /etl/output/dt=20180701 and /etl/output/dt=20180702</p>
  
  <p>But I want it to be /etl/output/20180701 and /etl/output/20180702</p>
  
  <p>Thanks</p>