title: Remove column names from spark dataframe while storing it as textfile
body: <p>My dataframe output is as below,<br>
  <code>DF.show(2)</code>  </p>
  
  <pre><code>+--------------+  
  |col1|col2|col3|  
  +--------------+  
  |  10|  20|  30|  
  |  11|  21|  31|  
  +--------------+ 
  </code></pre>
  
  <p>after saving it as textfile - DF.rdd.saveAsTextFile("path")  </p>
  
  <pre><code>Row(col1=u'10', col2=u'20', col3=u'30')  
  Row(col1=u'11', col2=u'21', col3=u'31')  
  </code></pre>
  
  <p>the dataframe has millions of rows and 20 columns, how can i save it as textfile as below, i.e., without column names and python unicodes  </p>
  
  <pre><code>10|20|30  
  11|21|31 
  </code></pre>
  
  <p>while creating initial RDD i used below code to remove unicodes, though still getting the unicodes,  </p>
  
  <pre><code>data = sc.textFile("file.txt")
  trans = data.map(lambda x: x.encode("ascii", "ignore").split("|"))  
  </code></pre>
  
  <p>Thanks in advance !</p>