This patch add a python script to calculate the time and the call
times from the command log file and syslog file.
Note: To get the correct data, the `dbtracelevel` option in site
table should be set to 4
implement: #3713
Support option:
```
usage: dbstats [--clusterlog CLUSTERLOG] [--commandlog COMMANDLOG] [-n NUM]
[-c COMMAND]
Optional arguments:
--clusterlog CLUSTERLOG
The syslog file of xcat.
--commandlog COMMANDLOG
The command log file of xcat.
-n NUM, --num NUM The recent count of commands to analyze
-c COMMAND, --command COMMAND
The specified command to track
```
