docs: def index_open(self, index):
          '''
          Opens the speicified index.
          http://www.elasticsearch.org/guide/reference/api/admin-indices-open-close.html
  
          > ElasticSearch().index_open('my_index')
          '''
          request = self.session
          url = 'http://%s:%s/%s/_open' % (self.host, self.port, index)
          response = request.post(url,None)
          return response