title: Elasticsearch list all rivers
body: <p><br>
  How do I list all the rivers in Elasticsearch, I'm new to it and was adding rivers on the fly and I want to do some cleaning.
  The <a href="http://www.elasticsearch.org/guide/en/elasticsearch/rivers/current/index.html" rel="nofollow">official documentation</a> doesn't mention a way to do so..</p>