title: Mapping configuration using elasticsearch-dsl DocType
body: <p>I'm developing a simple nlp tool, and using elasticsearch-dsl as a es tool with django. </p>
  
  <p>I will have two "DocType", Entity and Intent. I have created my own analyzer which is:</p>
  
  <pre><code>turkish_stop = token_filter('turkish_stop', type='stop', stopwords="_turkish_")
  turkish_lowercase = token_filter('turkish_lowercase', type='lowercase', language="turkish")
  turkish_stemmer = token_filter('turkish_stemmer', type='stemmer', language='turkish')
  
  turkish_analyzer = analyzer('turkish_analyzer', tokenizer='whitespace', filter=['apostrophe', 'asciifolding',
                                                                                  turkish_lowercase, turkish_stop,
                                                                                  turkish_stemmer])
  </code></pre>
  
  <p>In each doc, i have a custom mapping, for example;</p>
  
  <pre><code>class Entity(DocType):
      entity_synonyms = String(analyzer=es.turkish_analyzer, include_in_all=True)
      entity_key = String(index='not_analyzed', include_in_all=False)
  
      class Meta:
          index = es.ELASTICSEARCH_INDEX
          doc_type = es.ELASTICSEARCH_ENTITY_DOCTYPE
  </code></pre>
  
  <p>According to document <a href="http://elasticsearch-dsl.readthedocs.org/en/latest/persistence.html#persistence" rel="nofollow">http://elasticsearch-dsl.readthedocs.org/en/latest/persistence.html#persistence</a> . Entity.init() will create mapping for this doc. It really creates mapping on my es (only for entity doc! :( ) . However, i could not do same thing with Intent, after Entity.init(). 
  It gives below error:</p>
  
  <pre><code>IllegalOperation: You cannot update analysis configuration on an open index, you need to close index nlp first.
  </code></pre>
  
  <p>Any idea to solve this ? I really want to use Entity.init() and Intent.init() if it is possible.</p>