title: Find records with a start and end range covering the time now with ActiveRecord
body: <p>I'm working on a project dealing with opening hours of a store. I have <code>Store</code> and <code>OpeningHour</code> models, (<code>Store</code> <code>has_many</code> <code>OpeningHour</code>). The <code>opening_hours</code> table has <code>day</code>, <code>start</code> and <code>end</code> fields to store the day that <code>OpeningHour</code> record is to apply to, the time the store opens and the time the store closes. </p>
  
  <p>What would be the best way of finding any records where the time range set by <code>start</code> and <code>end</code> fields covers <code>Time.now</code>?</p>
  
  <p>Similar to the below conceptually:<br>
  <code>OpeningHour.where((start..end).cover? Time.now)</code></p>
  
  <p>Any help would be much appreciated!</p>