title: SPARK: Load master's directory on slave
body: <p>I would like to read an entire master's directory, on slaves.</p>
  
  <p>I know that, I can use sc.addFile and SparkFiles.get to read master's files on slaves.</p>
  
  <p><strong>Questions:</strong></p>
  
  <p>1) Is there the same for directory ?</p>
  
  <p>2) If not, is it possible to run functions on all the slaves of my cluster ?</p>