title: How to match the YYYY-MM-DDThh:mm:ssTZD timezone format in ruby
body: <p>I would like to check the iso8601 format for the date entered in ruby , like <strong>start_date = "2011/05/05"</strong> should be matched for the format <strong>2011-05-05T00:00:00-04:00</strong>  and errors returned accordingly. 
  Should we use regex here or any method is present for this?</p>