title: Spark output filename and append on write
body: <p>I know this question has been asked before but i am unable to get a clear working answer.</p>
  
  <pre><code>result.saveAsTextFile(path);
  </code></pre>
  
  <ol>
  <li><p>when using spark saveAsTextFile the output is saved by the name of "part-00", "part-01" etc. 
  Is it possible to change this name to customized name? </p></li>
  <li><p>Is it possible for a saveAsTextFile to append to existing file rather then overwriting it ?</p></li>
  </ol>
  
  <p><strong>I am using Java 7 for coding, the output file system would be cloud (Azure, Aws)</strong></p>