title: Sort Realm results by case insensitive property
body: <p>I'm sorting my results by a property called "alphabet" like this:</p>
  
  <pre><code>allArtists = Artist.allObjects().sortedResultsUsingProperty("alphabet", ascending: true)
  </code></pre>
  
  <p>How can I sort with case insensitive? Right now "cop" will appear before "Cat".</p>