[SPARK-5028][Streaming]Add total received and processed records metrics to Streaming UI

This is a follow-up work of [SPARK-4537](https://issues.apache.org/jira/browse/SPARK-4537). Adding total received records and processed records metrics back to UI.

![screenshot](https://dl.dropboxusercontent.com/u/19230832/screenshot.png)

Author: jerryshao <saisai.shao@intel.com>

Closes #3852 from jerryshao/SPARK-5028 and squashes the following commits:

c8c4877 [jerryshao] Add total received and processed metrics to Streaming UI

streaming/src/main/scala/org/apache/spark/streaming/ui/StreamingPage.scala

@@ -67,6 +67,12 @@ private[ui] class StreamingPage(parent: StreamingTab)
       <li>
         <strong>Waiting batches: </strong>{listener.numUnprocessedBatches}
       </li>
+      <li>
+        <strong>Received records: </strong>{listener.numTotalReceivedRecords}
+      </li>
+      <li>
+        <strong>Processed records: </strong>{listener.numTotalProcessedRecords}
+      </li>
     </ul>
   }