title: Firebase query for data within a date range
body: <p>My firebase data looks like this:</p>
  
  <pre><code>{
    "lambeosaurus": {
      "vacationDates" : "2016-12-20 - 2016-12-25",
      "length" : 12.5,
      "weight": 5000
    },
    "stegosaurus": {
      "vacationDates" : "2016-12-10 - 2016-12-20",
      "length" : 9,
      "weight" : 2500
    }
  }
  </code></pre>
  
  <p>How do i query for all dinosaurs that will be away on vacation on 2016-12-20 (i.e it should return both lambeosaurus and stegosaurus)? Or should I actually store the data differently? If so, how should I store the data for optimum performance? Thanks.</p>