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.

Change-Id: I3b50e1631e030a7ad67dd276c2e5e6ef33156f9a
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." into R1.10