title: Ordering an RDD[String]
body: <p>Consider</p>
  
  <pre><code>val animals = List("penguin","ferret","cat").toSeq
  val rdd = sc.makeRDD(animals, 1) 
  </code></pre>
  
  <p>I would like to order this RDD. I'm new to Scala and a little confused about how this is to be done.</p>