title: Cannot Start JanusGraph as per documentation
body: <p>I am using the <a href="http://docs.janusgraph.org/latest/getting-started.html" rel="nofollow noreferrer">Janus Graph doc</a> and I extracted it as mentioned.</p>
  
  <pre><code>./gremlin.sh
  </code></pre>
  
  <p>works fine and it starts the Gremlin prompt.</p>
  
  <p>This code also works fine</p>
  
  <pre><code>graph = JanusGraphFactory.open('inmemory')
  g = graph.traversal()
  </code></pre>
  
  <hr>
  
  <p><strong>Problem</strong></p>
  
  <p>When I do this, I get a huge stacktrace</p>
  
  <pre><code>graph = JanusGraphFactory.open('conf/janusgraph-berkeleyje-es.properties')
  
  
  gremlin&gt; graph = JanusGraphFactory.open('conf/janusgraph-berkeleyje-es.properties')
  12:15:49 WARN  org.janusgraph.diskstorage.es.rest.RestElasticSearchClient  - Unable to determine Elasticsearch server version. Default to FIVE.
  java.net.ConnectException: Connection refused
      at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
      at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
      at org.apache.http.impl.nio.reactor.DefaultConnectingIOReactor.processEvent(DefaultConnectingIOReactor.java:171)
      at org.apache.http.impl.nio.reactor.DefaultConnectingIOReactor.processEvents(DefaultConnectingIOReactor.java:145)
      at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor.execute(AbstractMultiworkerIOReactor.java:348)
      at org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionManager.execute(PoolingNHttpClientConnectionManager.java:192)
      at org.apache.http.impl.nio.client.CloseableHttpAsyncClientBase$1.run(CloseableHttpAsyncClientBase.java:64)
      at java.lang.Thread.run(Thread.java:748)
  Could not instantiate implementation: org.janusgraph.diskstorage.es.ElasticSearchIndex
  Type ':help' or ':h' for help.
  Display stack trace? [yN]
  </code></pre>