Add untar method to gearman client

Jenkins sends log files tarred and bz2 compressed, while gearman worker assumes
the log files are not tarred at all and gz compressed only.
1 add the loop to another method
2 move line 62-66 to the top of the loop
3 add default values to the `get` (if scp_location/log_path don't exist).
4 one tab indent in line 65