title: Support to convert time zone to IST from any other time zone in Ruby
body: <p>I,m using following versions of Ruby and Rails
  <strong>Ruby : 2.0.0p481</strong> &amp; 
  <strong>Rails : 4.1.1</strong></p>
  
  <p>Could not find any method in <strong>DateTime</strong> <code>class</code> to convert time to IST.</p>
  
  <p>Tried <code>DateTime.in_time_zone</code> in IRB, could convert IST to EST but not vise versa.</p>
  
  <pre><code>    2.0.0-p481 :003 &gt; date = "Thu Jan 07 2016 16:20:00 GMT+0530 (India Standard Time)"
      2.0.0-p481 :003 &gt; date = date.in_time_zone('Eastern Time (US &amp; Canada)')
      2.0.0-p481 :003 &gt; date
        =&gt; Thu, 07 Jan 2016 05:50:00 EST -05:00
  </code></pre>
  
  <p>Wanted to know how can I convert other tine zones to IST.
  Please let me know if there is any way from which I can achive this.</p>