[NGRINDER-658] Current test / error is not very clear 
http://jira.cubrid.org/browse/NGRINDER-658
[NGRINDER-659] Fix typo error
[NGRINDER-659] Fix typo error - adjust tps precision
[NGRINDER-656] Sampling interval should provide more than 5 seconds as
max value
- add 10, 30, 60