title: ElasticSearch: Is possible to return only value for i.e filtered count
body: <p>As in title:<br>
  Elasticsearch request:</p>
  
  <pre><code>localhost:9200/filebeat-*/_count?filter_path=-_shards
  </code></pre>
  
  <p>response:</p>
  
  <pre><code>{
  "count": 1390217
  }
  </code></pre>
  
  <p>Is possible to get only value when only one key:value pair is returned?</p>