title: Sort hash by key in descending order
body: <p>I have the following hash:</p>
  
  <pre><code>{"2013-08-12"=&gt; 10, "2013-08-13"=&gt; 20, "2013-11-11"=&gt;30, "2013-11-14"=&gt; 40} 
  </code></pre>
  
  <p>What I want to do is to sort it by key (dates in format yyyy-mm-dd) in descending order: </p>
  
  <pre><code>{"2013-11-14"=&gt; 40, "2013-11-11"=&gt;30, "2013-08-13"=&gt; 20, "2013-08-12"=&gt; 10} 
  </code></pre>
  
  <p>Is this possible?</p>