title: Add CharField to the search index in haystack
body: <p>I use in my django app (1.8), haystack (2.4.1) to search. And I want to be able to serach words with autocomplete (EdgeNgramField) and words when I put only the part of name, for example 'zo-zo on' (this isn't working with EdgeNgramField)</p>
  
  <p>Below I tired added: <code>text_sec = indexes.CharField(use_template=True)</code> but this isn't working for me.</p>
  
  <p>Here is my code, but he doesn't works:</p>
  
  <pre><code>class EventIndex(indexes.SearchIndex, indexes.Indexable):
      text = indexes.EdgeNgramField(document=True, use_template=True)
      text_sec = indexes.CharField(use_template=True)
      id = indexes.CharField(model_attr='id')
      get_absolute_url = indexes.CharField(model_attr='get_absolute_url')
      description = indexes.CharField(model_attr='description', null=True)
      is_past = indexes.CharField(model_attr='is_past', default='false')
      date_start = indexes.DateTimeField(model_attr='date_start')
  </code></pre>