Delets the specified index
        > search = ElasticSearch()
        > search.index_delete('twitter')
          {"ok" : True, "acknowledged" : True }

def index_delete(self, index):
        '''
        Delets the specified index
        > search = ElasticSearch()
        > search.index_delete('twitter')
          {"ok" : True, "acknowledged" : True }
        '''
        request = self.session
        url = 'http://%s:%s/%s' % (self.host, self.port, index)
        response = request.delete(url)
        return response