title: autocomplete light list shows only 20 items
body: <p>I integrated autocomplete light with my django app.</p>
  
  <p>In my registry i'm doing the following:</p>
  
  <pre><code>class HostAutocomplete( autocomplete_light.AutocompleteModelBase ):
      search_fields = [ 'hostname' ]
      choices = Host.objects.all()
  </code></pre>
  
  <p>In my form i have:</p>
  
  <pre><code>hosts=autocomplete_light.MultipleChoiceField('HostAutocomplete')
  </code></pre>
  
  <p>Autoocomplete is working fine but the list which i'm getting contains only 20 items. Database has many more entries. What could be the issue? </p>