title: Given a DateTime object, how do I get an ISO 8601 date in string format?
body: <p>Given:</p>
  
  <pre><code>DateTime.UtcNow
  </code></pre>
  
  <p>How do I get a string which represents the same value in an <a href="http://en.wikipedia.org/wiki/ISO_8601" rel="noreferrer">ISO 8601</a>-compliant format?</p>
  
  <p>Note that ISO 8601 defines a number of similar formats. The specific format I am looking for is:</p>
  
  <pre><code>yyyy-MM-ddTHH:mm:ssZ
  </code></pre>