title: Find all models across all namespaces
body: <p>I want to find all models in <em>all</em> namespaces.</p>
  
  <p>Ideas I've considered:</p>
  
  <ul>
  <li><p><code>Object.constants</code> is not working a good starting point because it does not find my namespaced modules. So <a href="https://stackoverflow.com/a/9853016/109618">this answer</a> isn't working for me.</p></li>
  <li><p><a href="http://www.ruby-doc.org/core-1.9.3/ObjectSpace.html" rel="nofollow noreferrer">ObjectSpace</a> is a possibility but I'd rather not use it unless necessary, since it seems less portable across Ruby implementations. (See also: <a href="http://kenai.com/projects/jruby/pages/PerformanceTuning#Disabling_ObjectSpace" rel="nofollow noreferrer">ObjectSpace is disabled by default in JRuby</a>.)</p></li>
  </ul>