title: What format does Facebook api return as "birthday"
body: <p>According to Facebook docs requesting birthday data is done by requesting <strong>user_birthday</strong> permission set and then the birthday string is stored under <strong>birthday</strong> in the return array. </p>
  
  <p>What format does it return in, and does the format vary according to users setting? </p>
  
  <p>Formats that I would predict</p>
  
  <pre><code>1990-05-22 // standard
  05.22.1990 // USA reverse format
  22.05 // User hid birth year
  1990 // Getting only birth year without a date
  NULL // User hid entire birthday
  </code></pre>
  
  <p>For me right now is important to determine whether Facebook gives one standard format of <strong>birthday</strong> value or its format depends on users birthday settings?</p>