Closes-Bug: #1373631
  Issue: Latency graphs would not dip when reads/writes were zero
  Fix: Individual read/write latency is sent using equation:
       (curr_latency_sum - prev_latency_sum)/(curr_count - prev_count)
       over average latency.
  Test: Dip was seen in latency graph after stopping the traffic with
        the above fix.
  Code change done based on review comments
  Code change done based on second review comments
  Code change done based on third review comments

Change-Id: I0155690fcaa782deb81ee4805bfd6dea3a907b93
Merge "Closes-Bug: #1373631   Issue: Latency graphs would not dip when reads/writes were zero   Fix: Individual read/write latency is sent using equation:        (curr_latency_sum - prev_latency_sum)/(curr_count - prev_count)        over average latency.   Test: Dip was seen in latency graph after stopping the traffic with         the above fix.   Code change done based on review comments   Code change done based on second review comments   Code change done based on third review comments"