title: MongoID find or find_by
body: <p>The MongoID <a href="http://mongoid.org/en/mongoid/docs/querying.html#queries" rel="noreferrer">docs</a> seem to be pretty clear that I should be able to run this and have it work:</p>
  
  <pre><code>Band.find_by(name: "Photek")
  </code></pre>
  
  <p>but at least with MongoID 2.4.11 this gives me a <code>NoMethodError</code>.</p>
  
  <p>This, on the other hand, works:</p>
  
  <pre><code>Band.find(name: "Photek")
  </code></pre>
  
  <p>It's easy enough to change <code>find_by</code> to <code>find</code>, but I'm confused what's going on.  Is this a case where my gem version is behind the docs, or what?</p>