title: Convert date with known timezone to UTC date
body: <p>Date and Time Conversion has always been my weak link. I have the following values in string format:</p>
  
  <ol>
  <li>String date="2015-08-21 03:15" and timezone for this date is</li>
  <li>String timeZone="GMT+05:30";</li>
  </ol>
  
  <p>Now I need to covert this date, for which I already know the timezone, to UTC date.</p>