[NO ISSUE][FUN] Return elapsedTime in Seconds

- user model changes: no
- storage format changes: no
- interface changes: no

Details:
- Return elapsedTime as a double in seconds in
  active/completed_requests functions' response
  rather than a string in milliseconds.

Change-Id: I412101ea43c1cbe13b15ed3ebb246af3c52e7b17
Reviewed-on: https://asterix-gerrit.ics.uci.edu/3348
Contrib: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Till Westmann <tillw@apache.org>
Sonar-Qube: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
diff --git a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/translator/BaseClientRequest.java b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/translator/BaseClientRequest.java
index 51971a5..eaca53b 100644
--- a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/translator/BaseClientRequest.java
+++ b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/translator/BaseClientRequest.java
@@ -97,7 +97,7 @@
         ObjectNode json = JSONUtil.createObject();
         json.put("uuid", requestReference.getUuid());
         json.put("requestTime", new ADateTime(requestReference.getTime()).toSimpleString());
-        json.put("elapsedTime", getElapsedTime());
+        json.put("elapsedTime", getElapsedTimeInSecs());
         json.put("node", requestReference.getNode());
         json.put("state", state.getLabel());
         json.put("userAgent", ((RequestReference) requestReference).getUserAgent());
@@ -106,11 +106,10 @@
         return json;
     }
 
-    private String getElapsedTime() {
+    private double getElapsedTimeInSecs() {
         // this is just an estimation as the request might have been received on a node with a different system time
-        // TODO add dynamic time unit
         long runningTime = completionTime > 0 ? completionTime : System.currentTimeMillis();
-        return runningTime - requestReference.getTime() + "ms";
+        return (runningTime - requestReference.getTime()) / 1000d;
     }
 
     protected abstract void doCancel(ICcApplicationContext appCtx) throws HyracksDataException;