title: How to compare times in different time zones in Ruby?
body: <p>I have this date that which is in timezone offset format that I need to convert to UTC format. 
  For example:</p>
  
  <p>date1 = 2017-07-13T17:13:12-04:00</p>
  
  <p>date2_utc = 2017-07-13 21:13:12 UTC</p>
  
  <p>I need to compare if those two date are same date. Or If I can convert date1 to UTC then i can compare those two.</p>