This bug is opened to provide relative query start time and end time. Th...

...e relative time can take values in the following format:

Now, now+10s,now+10m,now+10h,now-10s,now-10m,now-10h.
Diff Dummary:
1) We are retaining the same "start_time" and "end_time" to specify even the relative time 2)In opserver.py, start_time and end_time and converted to int in redis_query_status().Change has been made to retain them as string.
3) change has been made in calculation of time_slice. ^ operator was used instead of power() for exponent calculation, so replaced that as well.