title: PHP: Convert Local Time to UTC
body: <p>Assume I get a string like <code>08/22/2015 10:56 PM</code> and that this date/time string always refers to only one particular time zone. I need to be able to convert that to this format: <code>'Ymd\THis\Z'</code>, which is the iCal format.</p>
  
  <ol>
  <li>How do I convert that string to Zulu time and into <code>'Ymd\THis\Z'</code></li>
  <li>How do I then add, say, 30 minutes to that date/time?</li>
  </ol>
  
  <p>Been trying to hack this with strtotime and DateTime, but I'm worried that I'm going about this the wrong way. Maybe there's a simpler and more straightforward solution?</p>