title: Figure out day range from a start - end date and time (UTC)
body: <p>So I'm retrieving two values from a service which provide me with:</p>
  
  <p><code>start date/time: 1970-06-08T23:00:00Z</code></p>
  
  <p><code>end   date/time: 1970-06-13T07:00:00Z</code></p>
  
  <p>for example: tue-sat 08:00 - 16:00 | sun-thur 09:00 - 17:00</p>
  
  <p>any ideas how to work this out?</p>